feat(core): add parallelism to target configuration (#26820)

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## Current Behavior
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## Expected Behavior
<!-- This is the behavior we should expect with the changes in this PR
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## Related Issue(s)
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merged. -->

Fixes #

docs/generated/devkit/TargetConfiguration.md

@@ -22,6 +22,7 @@ Target's configuration
 - [metadata](../../devkit/documents/TargetConfiguration#metadata): TargetMetadata
 - [options](../../devkit/documents/TargetConfiguration#options): T
 - [outputs](../../devkit/documents/TargetConfiguration#outputs): string[]
+- [parallelism](../../devkit/documents/TargetConfiguration#parallelism): boolean
 
 ## Properties
 
@@ -109,3 +110,12 @@ Target's options. They are passed in to the executor.
 
 List of the target's outputs. The outputs will be cached by the Nx computation
 caching engine.
+
+---
+
+### parallelism
+
+• `Optional` **parallelism**: `boolean`
+
+Whether this target can be run in parallel with other tasks
+Default is true

docs/generated/devkit/Task.md

@@ -13,6 +13,7 @@ A representation of the invocation of an Executor
 - [id](../../devkit/documents/Task#id): string
 - [outputs](../../devkit/documents/Task#outputs): string[]
 - [overrides](../../devkit/documents/Task#overrides): any
+- [parallelism](../../devkit/documents/Task#parallelism): boolean
 - [projectRoot](../../devkit/documents/Task#projectroot): string
 - [startTime](../../devkit/documents/Task#starttime): number
 - [target](../../devkit/documents/Task#target): Object
@@ -84,6 +85,14 @@ Overrides for the configured options of the target
 
 ---
 
+### parallelism
+
+• **parallelism**: `boolean`
+
+Determines if a given task should be parallelizable.
+
+---
+
 ### projectRoot
 
 • `Optional` **projectRoot**: `string`

packages/cypress/src/plugins/plugin.spec.ts

@@ -121,6 +121,7 @@ describe('@nx/cypress/plugin', () => {
                       "{projectRoot}/dist/videos",
                       "{projectRoot}/dist/screenshots",
                     ],
+                    "parallelism": false,
                   },
                   "open-cypress": {
                     "command": "cypress open",
@@ -329,6 +330,7 @@ describe('@nx/cypress/plugin', () => {
                       "{projectRoot}/dist/videos",
                       "{projectRoot}/dist/screenshots",
                     ],
+                    "parallelism": false,
                   },
                   "e2e-ci": {
                     "cache": true,
@@ -369,6 +371,7 @@ describe('@nx/cypress/plugin', () => {
                       "{projectRoot}/dist/videos",
                       "{projectRoot}/dist/screenshots",
                     ],
+                    "parallelism": false,
                   },
                   "e2e-ci--src/test.cy.ts": {
                     "cache": true,
@@ -404,6 +407,7 @@ describe('@nx/cypress/plugin', () => {
                       "{projectRoot}/dist/videos",
                       "{projectRoot}/dist/screenshots",
                     ],
+                    "parallelism": false,
                   },
                   "open-cypress": {
                     "command": "cypress open",

packages/cypress/src/plugins/plugin.ts

@@ -211,6 +211,7 @@ async function buildCypressTargets(
       cache: true,
       inputs: getInputs(namedInputs),
       outputs: getOutputs(projectRoot, cypressConfig, 'e2e'),
+      parallelism: false,
       metadata: {
         technologies: ['cypress'],
         description: 'Runs Cypress Tests',
@@ -276,6 +277,7 @@ async function buildCypressTargets(
           options: {
             cwd: projectRoot,
           },
+          parallelism: false,
           metadata: {
             technologies: ['cypress'],
             description: `Runs Cypress Tests in ${relativeSpecFilePath} in CI`,
@@ -300,6 +302,7 @@ async function buildCypressTargets(
         inputs,
         outputs,
         dependsOn,
+        parallelism: false,
         metadata: {
           technologies: ['cypress'],
           description: 'Runs Cypress Tests in CI',

packages/js/src/utils/buildable-libs-utils.spec.ts

@@ -389,30 +389,35 @@ describe('calculateDependenciesFromTaskGraph', () => {
           overrides: {},
           target: { project: 'lib1', target: 'build' },
           outputs: [],
+          parallelism: true,
         },
         'lib2:build': {
           id: 'lib2:build',
           overrides: {},
           target: { project: 'lib2', target: 'build' },
           outputs: [],
+          parallelism: true,
         },
         'lib2:build-base': {
           id: 'lib2:build-base',
           overrides: {},
           target: { project: 'lib2', target: 'build-base' },
           outputs: [],
+          parallelism: true,
         },
         'lib3:build': {
           id: 'lib3:build',
           overrides: {},
           target: { project: 'lib3', target: 'build' },
           outputs: [],
+          parallelism: true,
         },
         'lib4:build': {
           id: 'lib4:build',
           overrides: {},
           target: { project: 'lib4', target: 'build' },
           outputs: [],
+          parallelism: true,
         },
       },
     };
@@ -559,48 +564,56 @@ describe('calculateDependenciesFromTaskGraph', () => {
           overrides: {},
           target: { project: 'lib1', target: 'build' },
           outputs: [],
+          parallelism: true,
         },
         'lib1:build-base': {
           id: 'lib1:build-base',
           overrides: {},
           target: { project: 'lib1', target: 'build-base' },
           outputs: [],
+          parallelism: true,
         },
         'lib2:build': {
           id: 'lib2:build',
           overrides: {},
           target: { project: 'lib2', target: 'build' },
           outputs: [],
+          parallelism: true,
         },
         'lib2:build-base': {
           id: 'lib2:build-base',
           overrides: {},
           target: { project: 'lib2', target: 'build-base' },
           outputs: [],
+          parallelism: true,
         },
         'lib3:build': {
           id: 'lib3:build',
           overrides: {},
           target: { project: 'lib3', target: 'build' },
           outputs: [],
+          parallelism: true,
         },
         'lib3:build-base': {
           id: 'lib3:build-base',
           overrides: {},
           target: { project: 'lib3', target: 'build-base' },
           outputs: [],
+          parallelism: true,
         },
         'lib4:build': {
           id: 'lib4:build',
           overrides: {},
           target: { project: 'lib4', target: 'build' },
           outputs: [],
+          parallelism: true,
         },
         'lib4:build-base': {
           id: 'lib4:build-base',
           overrides: {},
           target: { project: 'lib4', target: 'build-base' },
           outputs: [],
+          parallelism: true,
         },
       },
     };

packages/nx/schemas/project-schema.json

@@ -4,6 +4,27 @@
   "title": "JSON schema for Nx projects",
   "type": "object",
   "properties": {
+    "name": {
+      "type": "string",
+      "description": "Project's name. Optional if specified in workspace.json"
+    },
+    "root": {
+      "type": "string",
+      "description": "Project's location relative to the root of the workspace"
+    },
+    "sourceRoot": {
+      "type": "string",
+      "description": "The location of project's sources relative to the root of the workspace"
+    },
+    "projectType": {
+      "type": "string",
+      "description": "Type of project supported",
+      "enum": ["library", "application"]
+    },
+    "generators": {
+      "type": "object",
+      "description": "List of default values used by generators"
+    },
     "namedInputs": {
       "type": "object",
       "description": "Named inputs used by inputs defined in targets",
@@ -112,6 +133,11 @@
           "cache": {
             "type": "boolean",
             "description": "Specifies if the given target should be cacheable"
+          },
+          "parallelism": {
+            "type": "boolean",
+            "default": true,
+            "description": "Whether this target can be run in parallel with other tasks"
           }
         }
       }

packages/nx/src/config/task-graph.ts

@@ -76,6 +76,11 @@ export interface Task {
    * Determines if a given task should be cacheable.
    */
   cache?: boolean;
+
+  /**
+   * Determines if a given task should be parallelizable.
+   */
+  parallelism: boolean;
 }
 
 /**

packages/nx/src/config/to-project-name.spec.ts

@@ -73,6 +73,7 @@ describe('Workspaces', () => {
               ],
               "executor": "@nx/js:release-publish",
               "options": {},
+              "parallelism": true,
             },
           },
         }

packages/nx/src/config/workspace-json-project-json.ts

@@ -230,4 +230,10 @@ export interface TargetConfiguration<T = any> {
    * Metadata about the target
    */
   metadata?: TargetMetadata;
+
+  /**
+   * Whether this target can be run in parallel with other tasks
+   * Default is true
+   */
+  parallelism?: boolean;
 }

packages/nx/src/hasher/native-task-hasher-impl.spec.ts

@@ -155,21 +155,21 @@ describe('native task hasher', () => {
             "AllExternalDependencies": "3244421341483603138",
             "env:NONEXISTENTENV": "3244421341483603138",
             "env:TESTENV": "11441948532827618368",
-            "parent:ProjectConfiguration": "4131510303084753861",
+            "parent:ProjectConfiguration": "3608670998275221195",
             "parent:TsConfig": "2264969541778889434",
             "parent:{projectRoot}/**/*": "15295586939211629225",
             "runtime:echo runtime123": "29846575039086708",
-            "tagged:ProjectConfiguration": "1604492097835699503",
+            "tagged:ProjectConfiguration": "8596726088057301092",
             "tagged:TsConfig": "2264969541778889434",
             "tagged:{projectRoot}/**/*": "112200405683630828",
-            "unrelated:ProjectConfiguration": "439515135357674343",
+            "unrelated:ProjectConfiguration": "11133337791644294114",
             "unrelated:TsConfig": "2264969541778889434",
             "unrelated:{projectRoot}/**/*": "10505120368757496776",
             "{workspaceRoot}/.gitignore": "3244421341483603138",
             "{workspaceRoot}/.nxignore": "3244421341483603138",
             "{workspaceRoot}/nx.json": "5219582320960288192",
           },
-          "value": "6332317845632665670",
+          "value": "17193008237392864712",
         },
       ]
     `);
@@ -226,17 +226,17 @@ describe('native task hasher', () => {
       {
         "details": {
           "AllExternalDependencies": "3244421341483603138",
-          "child:ProjectConfiguration": "7051130583729928229",
+          "child:ProjectConfiguration": "710102491746666394",
           "child:TsConfig": "2264969541778889434",
           "child:{projectRoot}/**/*": "7694964870822928111",
-          "parent:ProjectConfiguration": "7704699416930647320",
+          "parent:ProjectConfiguration": "8031122597231773116",
           "parent:TsConfig": "2264969541778889434",
           "parent:{projectRoot}/**/*": "15295586939211629225",
           "{workspaceRoot}/.gitignore": "3244421341483603138",
           "{workspaceRoot}/.nxignore": "3244421341483603138",
           "{workspaceRoot}/nx.json": "5219582320960288192",
         },
-        "value": "18412450685244791672",
+        "value": "4141725338792606519",
       }
     `);
   });
@@ -307,17 +307,17 @@ describe('native task hasher', () => {
       {
         "details": {
           "AllExternalDependencies": "3244421341483603138",
-          "child:ProjectConfiguration": "2562552455862160288",
+          "child:ProjectConfiguration": "13051054958929525761",
           "child:TsConfig": "2264969541778889434",
           "child:{projectRoot}/**/*": "7694964870822928111",
           "parent:!{projectRoot}/**/*.spec.ts": "7663204892242899157",
-          "parent:ProjectConfiguration": "4131510303084753861",
+          "parent:ProjectConfiguration": "3608670998275221195",
           "parent:TsConfig": "2264969541778889434",
           "{workspaceRoot}/.gitignore": "3244421341483603138",
           "{workspaceRoot}/.nxignore": "3244421341483603138",
           "{workspaceRoot}/nx.json": "4641558175996703359",
         },
-        "value": "5825507912633865657",
+        "value": "12061654175538209437",
       }
     `);
   });
@@ -379,25 +379,25 @@ describe('native task hasher', () => {
           "details": {
             "AllExternalDependencies": "3244421341483603138",
             "parent:!{projectRoot}/**/*.spec.ts": "7663204892242899157",
-            "parent:ProjectConfiguration": "8008830016795210968",
+            "parent:ProjectConfiguration": "16402137858974842465",
             "parent:TsConfig": "2264969541778889434",
             "{workspaceRoot}/.gitignore": "3244421341483603138",
             "{workspaceRoot}/.nxignore": "3244421341483603138",
             "{workspaceRoot}/nx.json": "4641558175996703359",
           },
-          "value": "16919987205625802616",
+          "value": "1683972350273460485",
         },
         {
           "details": {
             "AllExternalDependencies": "3244421341483603138",
-            "parent:ProjectConfiguration": "8008830016795210968",
+            "parent:ProjectConfiguration": "16402137858974842465",
             "parent:TsConfig": "2264969541778889434",
             "parent:{projectRoot}/**/*": "15295586939211629225",
             "{workspaceRoot}/.gitignore": "3244421341483603138",
             "{workspaceRoot}/.nxignore": "3244421341483603138",
             "{workspaceRoot}/nx.json": "4641558175996703359",
           },
-          "value": "2732213649703581334",
+          "value": "2469956415584213984",
         },
       ]
     `);
@@ -478,10 +478,10 @@ describe('native task hasher', () => {
           "details": {
             "AllExternalDependencies": "3244421341483603138",
             "child:!{projectRoot}/**/*.spec.ts": "13790135045935437026",
-            "child:ProjectConfiguration": "11541456798478268276",
+            "child:ProjectConfiguration": "10085593111011845427",
             "child:TsConfig": "2264969541778889434",
             "env:MY_TEST_HASH_ENV": "17357374746554314488",
-            "parent:ProjectConfiguration": "2287392686890337925",
+            "parent:ProjectConfiguration": "14398811678394411425",
             "parent:TsConfig": "2264969541778889434",
             "parent:{projectRoot}/**/*": "15295586939211629225",
             "{workspaceRoot}/.gitignore": "3244421341483603138",
@@ -490,7 +490,7 @@ describe('native task hasher', () => {
             "{workspaceRoot}/global2": "13625885481717016690",
             "{workspaceRoot}/nx.json": "10897751101872977225",
           },
-          "value": "1217581064022758580",
+          "value": "12563443797830627612",
         },
       ]
     `);
@@ -539,14 +539,14 @@ describe('native task hasher', () => {
       {
         "details": {
           "AllExternalDependencies": "3244421341483603138",
-          "parent:ProjectConfiguration": "4131510303084753861",
+          "parent:ProjectConfiguration": "3608670998275221195",
           "parent:TsConfig": "8661678577354855152",
           "parent:{projectRoot}/**/*": "15295586939211629225",
           "{workspaceRoot}/.gitignore": "3244421341483603138",
           "{workspaceRoot}/.nxignore": "3244421341483603138",
           "{workspaceRoot}/nx.json": "5219582320960288192",
         },
-        "value": "9574395623667735815",
+        "value": "192468752006013407",
       }
     `);
   });
@@ -616,17 +616,17 @@ describe('native task hasher', () => {
       {
         "details": {
           "AllExternalDependencies": "3244421341483603138",
-          "child:ProjectConfiguration": "3898391056798628885",
+          "child:ProjectConfiguration": "13748859057138736105",
           "child:TsConfig": "2264969541778889434",
           "child:{projectRoot}/**/*": "7694964870822928111",
-          "parent:ProjectConfiguration": "4131510303084753861",
+          "parent:ProjectConfiguration": "3608670998275221195",
           "parent:TsConfig": "2264969541778889434",
           "parent:{projectRoot}/**/*": "15295586939211629225",
           "{workspaceRoot}/.gitignore": "3244421341483603138",
           "{workspaceRoot}/.nxignore": "3244421341483603138",
           "{workspaceRoot}/nx.json": "5219582320960288192",
         },
-        "value": "3140483997697830788",
+        "value": "571545311225175014",
       }
     `);
 
@@ -640,17 +640,17 @@ describe('native task hasher', () => {
       {
         "details": {
           "AllExternalDependencies": "3244421341483603138",
-          "child:ProjectConfiguration": "3898391056798628885",
+          "child:ProjectConfiguration": "13748859057138736105",
           "child:TsConfig": "2264969541778889434",
           "child:{projectRoot}/**/*": "7694964870822928111",
-          "parent:ProjectConfiguration": "4131510303084753861",
+          "parent:ProjectConfiguration": "3608670998275221195",
           "parent:TsConfig": "2264969541778889434",
           "parent:{projectRoot}/**/*": "15295586939211629225",
           "{workspaceRoot}/.gitignore": "3244421341483603138",
           "{workspaceRoot}/.nxignore": "3244421341483603138",
           "{workspaceRoot}/nx.json": "5219582320960288192",
         },
-        "value": "3140483997697830788",
+        "value": "571545311225175014",
       }
     `);
   });

packages/nx/src/hasher/task-hasher.spec.ts

@@ -121,6 +121,7 @@ describe('TaskHasher', () => {
         id: 'parent-build',
         overrides: { prop: 'prop-value' },
         outputs: [],
+        parallelism: true,
       },
       {
         roots: ['parent-build'],
@@ -130,6 +131,7 @@ describe('TaskHasher', () => {
             target: { project: 'parent', target: 'build' },
             overrides: {},
             outputs: [],
+            parallelism: true,
           },
         },
         dependencies: {},
@@ -188,6 +190,7 @@ describe('TaskHasher', () => {
         id: 'parent-build',
         overrides: { prop: 'prop-value' },
         outputs: [],
+        parallelism: true,
       },
       {
         roots: ['child-build'],
@@ -197,12 +200,14 @@ describe('TaskHasher', () => {
             target: { project: 'parent', target: 'build' },
             overrides: {},
             outputs: [],
+            parallelism: true,
           },
           'child-build': {
             id: 'child-build',
             target: { project: 'child', target: 'build' },
             overrides: {},
             outputs: [],
+            parallelism: true,
           },
         },
         dependencies: {
@@ -275,6 +280,7 @@ describe('TaskHasher', () => {
         id: 'parent-build',
         overrides: { prop: 'prop-value' },
         outputs: [],
+        parallelism: true,
       },
       {
         roots: ['child-build'],
@@ -284,12 +290,14 @@ describe('TaskHasher', () => {
             target: { project: 'parent', target: 'build' },
             overrides: {},
             outputs: [],
+            parallelism: true,
           },
           'child-build': {
             id: 'child-build',
             target: { project: 'child', target: 'build' },
             overrides: {},
             outputs: [],
+            parallelism: true,
           },
         },
         dependencies: {
@@ -354,6 +362,7 @@ describe('TaskHasher', () => {
           target: { project: 'parent', target: 'test' },
           overrides: {},
           outputs: [],
+          parallelism: true,
         },
       },
       dependencies: {},
@@ -365,6 +374,7 @@ describe('TaskHasher', () => {
         id: 'parent-test',
         overrides: { prop: 'prop-value' },
         outputs: [],
+        parallelism: true,
       },
       taskGraph,
       {}
@@ -378,6 +388,7 @@ describe('TaskHasher', () => {
         id: 'parent-build',
         overrides: { prop: 'prop-value' },
         outputs: [],
+        parallelism: true,
       },
       taskGraph,
       {}
@@ -459,12 +470,14 @@ describe('TaskHasher', () => {
           target: { project: 'parent', target: 'test' },
           overrides: {},
           outputs: [],
+          parallelism: true,
         },
         'child-test': {
           id: 'child-test',
           target: { project: 'child', target: 'test' },
           overrides: {},
           outputs: [],
+          parallelism: true,
         },
       },
       dependencies: {
@@ -478,6 +491,7 @@ describe('TaskHasher', () => {
         id: 'parent-test',
         overrides: { prop: 'prop-value' },
         outputs: [],
+        parallelism: true,
       },
       taskGraph,
       { MY_TEST_HASH_ENV: 'MY_TEST_HASH_ENV_VALUE' }
@@ -491,6 +505,7 @@ describe('TaskHasher', () => {
         id: 'child-test',
         overrides: { prop: 'prop-value' },
         outputs: [],
+        parallelism: true,
       },
       taskGraph,
       { MY_TEST_HASH_ENV: 'MY_TEST_HASH_ENV_VALUE' }
@@ -559,6 +574,7 @@ describe('TaskHasher', () => {
         id: 'parent-build',
         overrides: { prop: 'prop-value' },
         outputs: [],
+        parallelism: true,
       },
       {
         roots: ['child-build'],
@@ -568,12 +584,14 @@ describe('TaskHasher', () => {
             target: { project: 'parent', target: 'build' },
             overrides: {},
             outputs: [],
+            parallelism: true,
           },
           'child-build': {
             id: 'child-build',
             target: { project: 'child', target: 'build' },
             overrides: {},
             outputs: [],
+            parallelism: true,
           },
         },
         dependencies: {
@@ -622,6 +640,7 @@ describe('TaskHasher', () => {
         id: 'parent-build',
         overrides: { prop: 'prop-value' },
         outputs: [],
+        parallelism: true,
       },
       {
         roots: ['parent:build'],
@@ -631,6 +650,7 @@ describe('TaskHasher', () => {
             target: { project: 'parent', target: 'build' },
             overrides: {},
             outputs: [],
+            parallelism: true,
           },
         },
         dependencies: {},
@@ -687,12 +707,14 @@ describe('TaskHasher', () => {
           target: { project: 'parent', target: 'build' },
           overrides: {},
           outputs: [],
+          parallelism: true,
         },
         'child-build': {
           id: 'child-build',
           target: { project: 'child', target: 'build' },
           overrides: {},
           outputs: [],
+          parallelism: true,
         },
       },
       dependencies: {
@@ -706,6 +728,7 @@ describe('TaskHasher', () => {
         id: 'parent-build',
         overrides: { prop: 'prop-value' },
         outputs: [],
+        parallelism: true,
       },
       taskGraph,
       {}
@@ -719,6 +742,7 @@ describe('TaskHasher', () => {
         id: 'child-build',
         overrides: { prop: 'prop-value' },
         outputs: [],
+        parallelism: true,
       },
       taskGraph,
       {}
@@ -763,6 +787,7 @@ describe('TaskHasher', () => {
           id: 'parent-build',
           overrides: {},
           outputs: [],
+          parallelism: true,
         },
         {
           roots: ['parent:build'],
@@ -772,6 +797,7 @@ describe('TaskHasher', () => {
               target: { project: 'parent', target: 'build' },
               overrides: {},
               outputs: [],
+              parallelism: true,
             },
           },
           dependencies: {},
@@ -834,6 +860,7 @@ describe('TaskHasher', () => {
         id: 'app-build',
         overrides: { prop: 'prop-value' },
         outputs: [],
+        parallelism: true,
       },
       {
         roots: ['app-build'],
@@ -843,6 +870,7 @@ describe('TaskHasher', () => {
             target: { project: 'app', target: 'build' },
             overrides: {},
             outputs: [],
+            parallelism: true,
           },
         },
         dependencies: {},
@@ -902,6 +930,7 @@ describe('TaskHasher', () => {
         id: 'app-build',
         overrides: { prop: 'prop-value' },
         outputs: [],
+        parallelism: true,
       },
       {
         roots: ['app-build'],
@@ -911,6 +940,7 @@ describe('TaskHasher', () => {
             target: { project: 'app', target: 'build' },
             overrides: {},
             outputs: [],
+            parallelism: true,
           },
         },
         dependencies: {},
@@ -961,6 +991,7 @@ describe('TaskHasher', () => {
           id: 'app-build',
           overrides: { prop: 'prop-value' },
           outputs: [],
+          parallelism: true,
         },
         {
           roots: ['app-build'],
@@ -970,6 +1001,7 @@ describe('TaskHasher', () => {
               target: { project: 'app', target: 'build' },
               overrides: {},
               outputs: [],
+              parallelism: true,
             },
           },
           dependencies: {},
@@ -1051,12 +1083,14 @@ describe('TaskHasher', () => {
             target: { project: 'a', target: 'build' },
             overrides: {},
             outputs: [],
+            parallelism: true,
           },
           'b-build': {
             id: 'b-build',
             target: { project: 'b', target: 'build' },
             overrides: {},
             outputs: [],
+            parallelism: true,
           },
         },
         dependencies: {},
@@ -1071,6 +1105,7 @@ describe('TaskHasher', () => {
           target: { project: 'a', target: 'build' },
           overrides: {},
           outputs: [],
+          parallelism: true,
         },
         taskGraph,
         {}
@@ -1081,6 +1116,7 @@ describe('TaskHasher', () => {
           target: { project: 'b', target: 'build' },
           overrides: {},
           outputs: [],
+          parallelism: true,
         },
         taskGraph,
         {}
@@ -1092,6 +1128,7 @@ describe('TaskHasher', () => {
           target: { project: 'b', target: 'build' },
           overrides: {},
           outputs: [],
+          parallelism: true,
         },
         taskGraph,
         {}
@@ -1102,6 +1139,7 @@ describe('TaskHasher', () => {
           target: { project: 'a', target: 'build' },
           overrides: {},
           outputs: [],
+          parallelism: true,
         },
         taskGraph,
         {}
@@ -1201,6 +1239,7 @@ describe('TaskHasher', () => {
           id: 'app-build',
           overrides: { prop: 'prop-value' },
           outputs: [],
+          parallelism: true,
         },
         {
           roots: ['app-build'],
@@ -1210,6 +1249,7 @@ describe('TaskHasher', () => {
               target: { project: 'app', target: 'build' },
               overrides: {},
               outputs: [],
+              parallelism: true,
             },
           },
           dependencies: {},
@@ -1418,6 +1458,7 @@ describe('TaskHasher', () => {
           id: 'app-build',
           overrides: { prop: 'prop-value' },
           outputs: [],
+          parallelism: true,
         },
         {
           roots: ['app-build'],
@@ -1427,6 +1468,7 @@ describe('TaskHasher', () => {
               target: { project: 'app', target: 'build' },
               overrides: {},
               outputs: [],
+              parallelism: true,
             },
           },
           dependencies: {},
@@ -1502,6 +1544,7 @@ describe('TaskHasher', () => {
           id: 'app-build',
           overrides: { prop: 'prop-value' },
           outputs: [],
+          parallelism: true,
         },
         {
           roots: ['app-build'],
@@ -1511,6 +1554,7 @@ describe('TaskHasher', () => {
               target: { project: 'app', target: 'build' },
               overrides: {},
               outputs: [],
+              parallelism: true,
             },
           },
           dependencies: {},
@@ -1584,6 +1628,7 @@ describe('TaskHasher', () => {
           id: 'app-build',
           overrides: { prop: 'prop-value' },
           outputs: [],
+          parallelism: true,
         },
         {
           roots: ['app-build'],
@@ -1593,6 +1638,7 @@ describe('TaskHasher', () => {
               target: { project: 'app', target: 'build' },
               overrides: {},
               outputs: [],
+              parallelism: true,
             },
           },
           dependencies: {},
@@ -1710,6 +1756,7 @@ describe('TaskHasher', () => {
           id: 'parent-build',
           overrides: { prop: 'prop-value' },
           outputs: [],
+          parallelism: true,
         },
         {
           roots: ['grandchild-build'],
@@ -1719,18 +1766,21 @@ describe('TaskHasher', () => {
               target: { project: 'parent', target: 'build' },
               overrides: {},
               outputs: ['dist/libs/libs/parent'],
+              parallelism: true,
             },
             'child-build': {
               id: 'child-build',
               target: { project: 'child', target: 'build' },
               overrides: {},
               outputs: ['dist/libs/libs/child'],
+              parallelism: true,
             },
             'grandchild-build': {
               id: 'grandchild-build',
               target: { project: 'grandchild', target: 'build' },
               overrides: {},
               outputs: ['dist/libs/libs/grandchild'],
+              parallelism: true,
             },
           },
           dependencies: {
@@ -1850,6 +1900,7 @@ describe('TaskHasher', () => {
           id: 'parent-build',
           overrides: { prop: 'prop-value' },
           outputs: [],
+          parallelism: true,
         },
         {
           roots: ['grandchild-build'],
@@ -1859,18 +1910,21 @@ describe('TaskHasher', () => {
               target: { project: 'parent', target: 'build' },
               overrides: {},
               outputs: [],
+              parallelism: true,
             },
             'child-build': {
               id: 'child-build',
               target: { project: 'child', target: 'build' },
               overrides: {},
               outputs: [],
+              parallelism: true,
             },
             'grandchild-build': {
               id: 'grandchild-build',
               target: { project: 'grandchild', target: 'build' },
               overrides: {},
               outputs: [],
+              parallelism: true,
             },
           },
           dependencies: {

packages/nx/src/native/index.d.ts

@@ -185,6 +185,7 @@ export interface Target {
   outputs?: Array<string>
   options?: string
   configurations?: string
+  parallelism?: boolean
 }
 
 export interface Task {

packages/nx/src/native/project_graph/types.rs

@@ -16,6 +16,7 @@ pub struct Target {
     pub outputs: Option<Vec<String>>,
     pub options: Option<String>,
     pub configurations: Option<String>,
+    pub parallelism: Option<bool>,
 }
 
 #[napi(object)]

packages/nx/src/native/tasks/hashers/hash_project_config.rs

@@ -21,12 +21,13 @@ pub fn hash_project_config(
         .sorted_by(|a, b| a.0.cmp(b.0))
         .map(|(k, v)| {
             format!(
-                "{}{}{}{}{}",
+                "{}{}{}{}{}{}",
                 k,
                 v.executor.as_deref().unwrap_or_default(),
                 v.outputs.as_deref().unwrap_or_default().concat(),
                 v.options.as_deref().unwrap_or_default(),
                 v.configurations.as_deref().unwrap_or_default(),
+                v.parallelism.unwrap_or_default()
             )
         })
         .collect::<Vec<_>>()
@@ -144,7 +145,7 @@ mod tests {
         assert_eq!(nx_project_hash.unwrap(), "3244421341483603138");
 
         let js_project_hash = hash_project_config("js", &projects).unwrap();
-        assert_eq!(js_project_hash, "18342193044952101577");
+        assert_eq!(js_project_hash, "13565578942842640362");
 
         let js_unsorted = hash_project_config("js-unsorted", &projects);
         assert_eq!(js_unsorted.unwrap(), js_project_hash);

packages/nx/src/native/transform-objects.ts

@@ -23,6 +23,7 @@ export function transformProjectGraphForRust(
         outputs: targetConfig.outputs,
         options: JSON.stringify(targetConfig.options),
         configurations: JSON.stringify(targetConfig.configurations),
+        parallelism: targetConfig.parallelism,
       };
     }
     nodes[projectName] = {

packages/nx/src/project-graph/utils/project-configuration-utils.spec.ts

@@ -1520,6 +1520,7 @@ describe('project-configuration-utils', () => {
           "options": {
             "command": "echo libs/project",
           },
+          "parallelism": true,
         }
       `);
     });
@@ -1676,6 +1677,7 @@ describe('project-configuration-utils', () => {
           "options": {
             "command": "echo a @ libs/a",
           },
+          "parallelism": true,
         }
       `);
     });

packages/nx/src/project-graph/utils/project-configuration-utils.ts

@@ -1122,5 +1122,7 @@ export function normalizeTarget(
     );
   }
 
+  target.parallelism ??= true;
+
   return target;
 }

packages/nx/src/tasks-runner/create-task-graph.spec.ts

@@ -107,6 +107,7 @@ describe('createTaskGraph', () => {
           outputs: [],
           overrides: { a: 123 },
           projectRoot: 'app1-root',
+          parallelism: true,
         },
       },
       dependencies: {
@@ -137,6 +138,7 @@ describe('createTaskGraph', () => {
           outputs: [],
           overrides: { a: 123 },
           projectRoot: 'app1-root',
+          parallelism: true,
         },
         'lib1:test': {
           id: 'lib1:test',
@@ -147,6 +149,7 @@ describe('createTaskGraph', () => {
           outputs: [],
           overrides: { a: 123 },
           projectRoot: 'lib1-root',
+          parallelism: true,
         },
       },
       dependencies: {
@@ -286,6 +289,7 @@ describe('createTaskGraph', () => {
           outputs: [],
           overrides: {},
           projectRoot: 'lib1-root',
+          parallelism: true,
         },
         'lib2:compile': {
           id: 'lib2:compile',
@@ -298,6 +302,7 @@ describe('createTaskGraph', () => {
             __overrides_unparsed__: [],
           },
           projectRoot: 'lib2-root',
+          parallelism: true,
         },
       },
       dependencies: {
@@ -328,6 +333,7 @@ describe('createTaskGraph', () => {
           outputs: [],
           overrides: {},
           projectRoot: 'app1-root',
+          parallelism: true,
         },
         'lib1:compile:libDefault': {
           id: 'lib1:compile:libDefault',
@@ -341,6 +347,7 @@ describe('createTaskGraph', () => {
             __overrides_unparsed__: [],
           },
           projectRoot: 'lib1-root',
+          parallelism: true,
         },
         'lib2:compile:ci': {
           id: 'lib2:compile:ci',
@@ -354,6 +361,7 @@ describe('createTaskGraph', () => {
             __overrides_unparsed__: [],
           },
           projectRoot: 'lib2-root',
+          parallelism: true,
         },
       },
       dependencies: {
@@ -454,6 +462,7 @@ describe('createTaskGraph', () => {
             project: 'app1',
             target: 'compile',
           },
+          parallelism: true,
         },
         'lib3:compile': {
           id: 'lib3:compile',
@@ -466,6 +475,7 @@ describe('createTaskGraph', () => {
             project: 'lib3',
             target: 'compile',
           },
+          parallelism: true,
         },
       },
     });
@@ -494,6 +504,7 @@ describe('createTaskGraph', () => {
           outputs: [],
           overrides: { a: '--value=app1-root' },
           projectRoot: 'app1-root',
+          parallelism: true,
         },
       },
       dependencies: {
@@ -525,6 +536,7 @@ describe('createTaskGraph', () => {
           outputs: [],
           overrides: { a: '--base-href=/app1-root${deploymentId}' },
           projectRoot: 'app1-root',
+          parallelism: true,
         },
       },
       dependencies: {
@@ -639,6 +651,7 @@ describe('createTaskGraph', () => {
           outputs: [],
           overrides: { myFlag: 'flag value' },
           projectRoot: 'app1-root',
+          parallelism: true,
         },
         'app1:precompile': {
           id: 'app1:precompile',
@@ -649,6 +662,7 @@ describe('createTaskGraph', () => {
           outputs: [],
           overrides: { myFlag: 'flag value' },
           projectRoot: 'app1-root',
+          parallelism: true,
         },
         'lib1:compile': {
           id: 'lib1:compile',
@@ -659,6 +673,7 @@ describe('createTaskGraph', () => {
           outputs: [],
           overrides: { myFlag: 'flag value' },
           projectRoot: 'lib1-root',
+          parallelism: true,
         },
         'lib2:compile': {
           id: 'lib2:compile',
@@ -669,6 +684,7 @@ describe('createTaskGraph', () => {
           outputs: [],
           overrides: { __overrides_unparsed__: [] },
           projectRoot: 'lib2-root',
+          parallelism: true,
         },
       },
       dependencies: {
@@ -706,6 +722,7 @@ describe('createTaskGraph', () => {
             __overrides_unparsed__: [],
           },
           projectRoot: 'app1-root',
+          parallelism: true,
         },
         'app1:precompile': {
           id: 'app1:precompile',
@@ -718,6 +735,7 @@ describe('createTaskGraph', () => {
             __overrides_unparsed__: [],
           },
           projectRoot: 'app1-root',
+          parallelism: true,
         },
         'app1:precompile2': {
           id: 'app1:precompile2',
@@ -730,6 +748,7 @@ describe('createTaskGraph', () => {
             __overrides_unparsed__: [],
           },
           projectRoot: 'app1-root',
+          parallelism: true,
         },
         'lib1:compile': {
           id: 'lib1:compile',
@@ -742,6 +761,7 @@ describe('createTaskGraph', () => {
             __overrides_unparsed__: [],
           },
           projectRoot: 'lib1-root',
+          parallelism: true,
         },
       },
       dependencies: {
@@ -779,6 +799,7 @@ describe('createTaskGraph', () => {
             __overrides_unparsed__: [],
           },
           projectRoot: 'app1-root',
+          parallelism: true,
         },
         'app1:precompile': {
           id: 'app1:precompile',
@@ -791,6 +812,7 @@ describe('createTaskGraph', () => {
             __overrides_unparsed__: [],
           },
           projectRoot: 'app1-root',
+          parallelism: true,
         },
         'app1:precompile2': {
           id: 'app1:precompile2',
@@ -803,6 +825,7 @@ describe('createTaskGraph', () => {
             __overrides_unparsed__: [],
           },
           projectRoot: 'app1-root',
+          parallelism: true,
         },
         'lib1:compile': {
           id: 'lib1:compile',
@@ -815,6 +838,7 @@ describe('createTaskGraph', () => {
             __overrides_unparsed__: [],
           },
           projectRoot: 'lib1-root',
+          parallelism: true,
         },
       },
       dependencies: {
@@ -921,6 +945,7 @@ describe('createTaskGraph', () => {
             __overrides_unparsed__: [],
           },
           projectRoot: 'app1-root',
+          parallelism: true,
         },
         'lib1:compile': {
           id: 'lib1:compile',
@@ -933,6 +958,7 @@ describe('createTaskGraph', () => {
             __overrides_unparsed__: [],
           },
           projectRoot: 'lib1-root',
+          parallelism: true,
         },
         'lib2:compile': {
           id: 'lib2:compile',
@@ -945,6 +971,7 @@ describe('createTaskGraph', () => {
             __overrides_unparsed__: [],
           },
           projectRoot: 'lib2-root',
+          parallelism: true,
         },
         'lib3:compile': {
           id: 'lib3:compile',
@@ -957,6 +984,7 @@ describe('createTaskGraph', () => {
             __overrides_unparsed__: [],
           },
           projectRoot: 'lib3-root',
+          parallelism: true,
         },
       },
       dependencies: {
@@ -1080,6 +1108,7 @@ describe('createTaskGraph', () => {
           projectRoot: 'infra1-root',
           outputs: [],
           overrides: { myFlag: 'flag value' },
+          parallelism: true,
         },
         'app2:compile': {
           id: 'app2:compile',
@@ -1087,6 +1116,7 @@ describe('createTaskGraph', () => {
           projectRoot: 'app2-root',
           outputs: [],
           overrides: { __overrides_unparsed__: [] },
+          parallelism: true,
         },
         'coreInfra:apply': {
           id: 'coreInfra:apply',
@@ -1094,6 +1124,7 @@ describe('createTaskGraph', () => {
           projectRoot: 'infra3-root',
           outputs: [],
           overrides: { myFlag: 'flag value' },
+          parallelism: true,
         },
         'app1:compile': {
           id: 'app1:compile',
@@ -1101,6 +1132,7 @@ describe('createTaskGraph', () => {
           projectRoot: 'app1-root',
           outputs: [],
           overrides: { __overrides_unparsed__: [] },
+          parallelism: true,
         },
         'infra2:apply': {
           id: 'infra2:apply',
@@ -1108,6 +1140,7 @@ describe('createTaskGraph', () => {
           projectRoot: 'infra2-root',
           outputs: [],
           overrides: { myFlag: 'flag value' },
+          parallelism: true,
         },
       },
       dependencies: {
@@ -1174,6 +1207,7 @@ describe('createTaskGraph', () => {
             __overrides_unparsed__: [],
           },
           projectRoot: 'app1-root',
+          parallelism: true,
         },
         'app1:test': {
           id: 'app1:test',
@@ -1186,6 +1220,7 @@ describe('createTaskGraph', () => {
             __overrides_unparsed__: [],
           },
           projectRoot: 'app1-root',
+          parallelism: true,
         },
       },
       dependencies: {
@@ -1267,6 +1302,7 @@ describe('createTaskGraph', () => {
             __overrides_unparsed__: [],
           },
           projectRoot: 'app1-root',
+          parallelism: true,
         },
         'app3:compile': {
           id: 'app3:compile',
@@ -1279,6 +1315,7 @@ describe('createTaskGraph', () => {
             __overrides_unparsed__: [],
           },
           projectRoot: 'app3-root',
+          parallelism: true,
         },
       },
       dependencies: {
@@ -1357,6 +1394,7 @@ describe('createTaskGraph', () => {
             __overrides_unparsed__: [],
           },
           projectRoot: 'app1-root',
+          parallelism: true,
         },
         'app3:compile': {
           id: 'app3:compile',
@@ -1369,6 +1407,7 @@ describe('createTaskGraph', () => {
             __overrides_unparsed__: [],
           },
           projectRoot: 'app3-root',
+          parallelism: true,
         },
       },
       dependencies: {
@@ -1445,6 +1484,7 @@ describe('createTaskGraph', () => {
             __overrides_unparsed__: [],
           },
           projectRoot: 'app1-root',
+          parallelism: true,
         },
       },
       dependencies: {
@@ -1478,6 +1518,7 @@ describe('createTaskGraph', () => {
             __overrides_unparsed__: [],
           },
           projectRoot: 'app1-root',
+          parallelism: true,
         },
         'app2:compile': {
           id: 'app2:compile',
@@ -1490,6 +1531,7 @@ describe('createTaskGraph', () => {
             __overrides_unparsed__: [],
           },
           projectRoot: 'app2-root',
+          parallelism: true,
         },
       },
       dependencies: {

packages/nx/src/tasks-runner/create-task-graph.ts

@@ -35,7 +35,7 @@ export class ProcessTasks {
     configuration: string,
     overrides: Object,
     excludeTaskDependencies: boolean
-  ) {
+  ): string[] {
     for (const projectName of projectNames) {
       for (const target of targets) {
         const project = this.projectGraph.nodes[projectName];
@@ -319,6 +319,7 @@ export class ProcessTasks {
         interpolatedOverrides
       ),
       cache: project.data.targets[target].cache,
+      parallelism: project.data.targets[target].parallelism ?? true,
     };
   }
 

packages/nx/src/tasks-runner/tasks-schedule.spec.ts

@@ -5,7 +5,7 @@ import { DependencyType, ProjectGraph } from '../config/project-graph';
 import * as nxJsonUtils from '../config/nx-json';
 import * as executorUtils from '../command-line/run/executor-utils';
 
-function createMockTask(id: string): Task {
+function createMockTask(id: string, parallelism: boolean = true): Task {
   const [project, target] = id.split(':');
   return {
     id,
@@ -15,6 +15,7 @@ function createMockTask(id: string): Task {
     },
     outputs: [],
     overrides: {},
+    parallelism,
   };
 }
 
@@ -411,4 +412,367 @@ describe('TasksSchedule', () => {
       });
     });
   });
+
+  describe('tasks with parallelism false', () => {
+    describe('dependent tasks', () => {
+      let taskSchedule: TasksSchedule;
+      let taskGraph: TaskGraph;
+      let app1Build: Task;
+      let app2Build: Task;
+      let lib1Build: Task;
+      let lifeCycle: any;
+      beforeEach(() => {
+        // app1 depends on lib1
+        // app2 does not depend on anything
+        // lib1 does not depend on anything
+        // all tasks have parallelism set to false
+        app1Build = createMockTask('app1:build', false);
+        app2Build = createMockTask('app2:build', false);
+        lib1Build = createMockTask('lib1:build', false);
+
+        taskGraph = {
+          tasks: {
+            'app1:build': app1Build,
+            'app2:build': app2Build,
+            'lib1:build': lib1Build,
+          },
+          dependencies: {
+            'app1:build': ['lib1:build'],
+            'app2:build': [],
+            'lib1:build': [],
+          },
+          roots: ['lib1:build', 'app2:build'],
+        };
+        jest.spyOn(nxJsonUtils, 'readNxJson').mockReturnValue({});
+        jest.spyOn(executorUtils, 'getExecutorInformation').mockReturnValue({
+          schema: {
+            version: 2,
+            properties: {},
+          },
+          implementationFactory: jest.fn(),
+          batchImplementationFactory: jest.fn(),
+          isNgCompat: true,
+          isNxExecutor: true,
+        });
+
+        const projectGraph: ProjectGraph = {
+          nodes: {
+            app1: {
+              data: {
+                root: 'app1',
+                targets: {
+                  build: {
+                    executor: 'awesome-executors:build',
+                  },
+                },
+              },
+              name: 'app1',
+              type: 'app',
+            },
+            app2: {
+              name: 'app2',
+              type: 'app',
+              data: {
+                root: 'app2',
+                targets: {
+                  build: {
+                    executor: 'awesome-executors:app2-build',
+                  },
+                },
+              },
+            },
+            lib1: {
+              name: 'lib1',
+              type: 'lib',
+              data: {
+                root: 'lib1',
+                targets: {
+                  build: {
+                    executor: 'awesome-executors:build',
+                  },
+                },
+              },
+            },
+          } as any,
+          dependencies: {
+            app1: [
+              {
+                source: 'app1',
+                target: 'lib1',
+                type: DependencyType.static,
+              },
+            ],
+            app2: [
+              {
+                source: 'app2',
+                target: 'lib1',
+                type: DependencyType.static,
+              },
+            ],
+          },
+          externalNodes: {},
+          version: '5',
+        };
+
+        lifeCycle = {
+          startTask: jest.fn(),
+          endTask: jest.fn(),
+          scheduleTask: jest.fn(),
+        };
+        taskSchedule = new TasksSchedule(projectGraph, taskGraph, {
+          lifeCycle,
+        });
+      });
+
+      describe('Without Batch Mode', () => {
+        let original;
+        beforeEach(() => {
+          original = process.env['NX_BATCH_MODE'];
+          process.env['NX_BATCH_MODE'] = 'false';
+        });
+
+        afterEach(() => {
+          process.env['NX_BATCH_MODE'] = original;
+        });
+
+        it('should begin with no scheduled tasks', () => {
+          expect(taskSchedule.nextBatch()).toBeNull();
+          expect(taskSchedule.nextTask()).toBeNull();
+        });
+
+        it('should schedule root tasks first', async () => {
+          // app1 depends on lib1, app2 has no dependencies
+          await taskSchedule.scheduleNextTasks();
+          expect(taskSchedule.nextTask()).toEqual(lib1Build);
+          // since lib1 is not parallel, app2 should not be scheduled even though it has no dependencies
+          expect(taskSchedule.nextTask()).toBeNull();
+          taskSchedule.complete([lib1Build.id]);
+          await taskSchedule.scheduleNextTasks();
+          expect(taskSchedule.nextTask()).toEqual(app1Build);
+          expect(taskSchedule.nextTask()).toBeNull(); // app2 should not be scheduled since app1 is not parallel and not completed
+          taskSchedule.complete([app1Build.id]);
+          await taskSchedule.scheduleNextTasks();
+          expect(taskSchedule.nextTask()).toEqual(app2Build);
+          taskSchedule.complete([app2Build.id]);
+          expect(taskSchedule.hasTasks()).toEqual(false);
+        });
+
+        it('should not schedule batches', async () => {
+          await taskSchedule.scheduleNextTasks();
+
+          expect(taskSchedule.nextTask()).not.toBeNull();
+
+          expect(taskSchedule.nextBatch()).toBeNull();
+        });
+      });
+
+      describe('With Batch Mode', () => {
+        let original;
+        beforeEach(() => {
+          original = process.env['NX_BATCH_MODE'];
+          process.env['NX_BATCH_MODE'] = 'true';
+        });
+
+        afterEach(() => {
+          process.env['NX_BATCH_MODE'] = original;
+        });
+
+        it('should not schedule batches of tasks by different executors if task has parallelism false', async () => {
+          await taskSchedule.scheduleNextTasks();
+
+          // since all tasks have parallelism false, they should not be batched
+          expect(taskSchedule.nextTask()).toEqual(lib1Build);
+
+          expect(taskSchedule.nextBatch()).toBeNull();
+        });
+      });
+    });
+
+    describe('non-dependent tasks', () => {
+      let taskSchedule: TasksSchedule;
+      let taskGraph: TaskGraph;
+      let app1Test: Task;
+      let app2Test: Task;
+      let lib1Test: Task;
+      let lifeCycle: any;
+      beforeEach(() => {
+        // app1, app2, and lib1 do not depend on each other
+        // all tasks have parallelism set to false
+        app1Test = createMockTask('app1:test', false);
+        app2Test = createMockTask('app2:test', false);
+        lib1Test = createMockTask('lib1:test', false);
+
+        taskGraph = {
+          tasks: {
+            'app1:test': app1Test,
+            'app2:test': app2Test,
+            'lib1:test': lib1Test,
+          },
+          dependencies: {
+            'app1:test': [],
+            'app2:test': [],
+            'lib1:test': [],
+          },
+          roots: ['app1:test', 'app2:test', 'lib1:test'],
+        };
+        jest.spyOn(nxJsonUtils, 'readNxJson').mockReturnValue({});
+        jest.spyOn(executorUtils, 'getExecutorInformation').mockReturnValue({
+          schema: {
+            version: 2,
+            properties: {},
+          },
+          implementationFactory: jest.fn(),
+          batchImplementationFactory: jest.fn(),
+          isNgCompat: true,
+          isNxExecutor: true,
+        });
+
+        const projectGraph: ProjectGraph = {
+          nodes: {
+            app1: {
+              data: {
+                root: 'app1',
+                targets: {
+                  test: {
+                    executor: 'awesome-executors:test',
+                    parallelism: false,
+                  },
+                },
+              },
+              name: 'app1',
+              type: 'app',
+            },
+            app2: {
+              name: 'app2',
+              type: 'app',
+              data: {
+                root: 'app2',
+                targets: {
+                  test: {
+                    executor: 'awesome-executors:app2-test',
+                    parallelism: false,
+                  },
+                },
+              },
+            },
+            lib1: {
+              name: 'lib1',
+              type: 'lib',
+              data: {
+                root: 'lib1',
+                targets: {
+                  test: {
+                    executor: 'awesome-executors:test',
+                  },
+                },
+              },
+            },
+          } as any,
+          dependencies: {
+            app1: [
+              {
+                source: 'app1',
+                target: 'lib1',
+                type: DependencyType.static,
+              },
+            ],
+            app2: [
+              {
+                source: 'app2',
+                target: 'lib1',
+                type: DependencyType.static,
+              },
+            ],
+          },
+          externalNodes: {},
+          version: '5',
+        };
+
+        lifeCycle = {
+          startTask: jest.fn(),
+          endTask: jest.fn(),
+          scheduleTask: jest.fn(),
+        };
+        taskSchedule = new TasksSchedule(projectGraph, taskGraph, {
+          lifeCycle,
+        });
+      });
+
+      describe('Without Batch Mode', () => {
+        let original;
+        beforeEach(() => {
+          original = process.env['NX_BATCH_MODE'];
+          process.env['NX_BATCH_MODE'] = 'false';
+        });
+
+        afterEach(() => {
+          process.env['NX_BATCH_MODE'] = original;
+        });
+
+        it('should begin with no scheduled tasks', () => {
+          expect(taskSchedule.nextBatch()).toBeNull();
+          expect(taskSchedule.nextTask()).toBeNull();
+        });
+
+        it('should schedule root tasks in topological order', async () => {
+          await taskSchedule.scheduleNextTasks();
+          expect(taskSchedule.nextTask()).toEqual(app1Test);
+          let nextTask = taskSchedule.nextTask();
+          expect(nextTask).not.toEqual(app2Test); // app2 should not be scheduled since app1 is not parallel and not completed
+          expect(nextTask).not.toEqual(lib1Test); // lib1 should not be scheduled since app1 is not parallel and not completed
+          expect(nextTask).toBeNull();
+
+          taskSchedule.complete([app1Test.id]);
+          await taskSchedule.scheduleNextTasks();
+          nextTask = taskSchedule.nextTask();
+          expect(nextTask).toEqual(app2Test); // app2 should be scheduled since app1 is completed now
+
+          nextTask = taskSchedule.nextTask();
+          expect(nextTask).not.toEqual(lib1Test); // lib1 should not be scheduled since app2 is not parallel and not completed
+          expect(nextTask).toBeNull();
+
+          taskSchedule.complete([app1Test.id]); // this should not do anything since app1 is already completed
+          await taskSchedule.scheduleNextTasks();
+          nextTask = taskSchedule.nextTask();
+          expect(nextTask).not.toEqual(lib1Test); // lib1 should not be scheduled since app2 is not parallel and not completed
+          expect(nextTask).toBeNull();
+
+          taskSchedule.complete([app2Test.id]);
+          await taskSchedule.scheduleNextTasks();
+          expect(taskSchedule.nextTask()).toEqual(lib1Test); // lib1 should be scheduled since app2 is completed now
+          taskSchedule.complete([lib1Test.id]);
+          expect(taskSchedule.hasTasks()).toEqual(false);
+        });
+
+        it('should not schedule batches', async () => {
+          await taskSchedule.scheduleNextTasks();
+
+          expect(taskSchedule.nextTask()).not.toBeNull();
+
+          expect(taskSchedule.nextBatch()).toBeNull();
+        });
+      });
+
+      describe('With Batch Mode', () => {
+        let original;
+        beforeEach(() => {
+          original = process.env['NX_BATCH_MODE'];
+          process.env['NX_BATCH_MODE'] = 'true';
+        });
+
+        afterEach(() => {
+          process.env['NX_BATCH_MODE'] = original;
+        });
+
+        it('should not schedule batches of tasks by different executors if task have parallelism false', async () => {
+          await taskSchedule.scheduleNextTasks();
+
+          // app1, app2, and lib1 are not parallel, so they should not be batched
+          expect(taskSchedule.nextTask()).toEqual(app1Test);
+
+          expect(taskSchedule.nextBatch()).toBeNull();
+        });
+      });
+    });
+  });
 });

packages/nx/src/tasks-runner/tasks-schedule.ts

@@ -21,6 +21,7 @@ export class TasksSchedule {
   private reverseProjectGraph = reverse(this.projectGraph);
   private scheduledBatches: Batch[] = [];
   private scheduledTasks: string[] = [];
+  private runningTasks = new Set<string>();
   private completedTasks = new Set<string>();
   private scheduleRequestsExecutionChain = Promise.resolve();
 
@@ -48,6 +49,7 @@ export class TasksSchedule {
   public complete(taskIds: string[]) {
     for (const taskId of taskIds) {
       this.completedTasks.add(taskId);
+      this.runningTasks.delete(taskId);
     }
     this.notScheduledTaskGraph = removeTasksFromTaskGraph(
       this.notScheduledTaskGraph,
@@ -117,6 +119,7 @@ export class TasksSchedule {
             .length
         );
       });
+    this.runningTasks.add(taskId);
   }
 
   private async scheduleBatches() {
@@ -146,8 +149,8 @@ export class TasksSchedule {
     task: Task,
     rootExecutorName: string,
     isRoot: boolean
-  ) {
+  ): Promise<void> {
-    if (!this.canBatchTaskBeScheduled(task.id, batches[rootExecutorName])) {
+    if (!this.canBatchTaskBeScheduled(task, batches[rootExecutorName])) {
       return;
     }
 
@@ -191,18 +194,45 @@ export class TasksSchedule {
   }
 
   private canBatchTaskBeScheduled(
-    taskId: string,
+    task: Task,
     batchTaskGraph: TaskGraph | undefined
   ): boolean {
+    // task self needs to have parallelism true
     // all deps have either completed or belong to the same batch
-    return this.taskGraph.dependencies[taskId].every(
+    return (
+      task.parallelism === true &&
+      this.taskGraph.dependencies[task.id].every(
         (id) => this.completedTasks.has(id) || !!batchTaskGraph?.tasks[id]
+      )
     );
   }
 
-  private canBeScheduled(taskId: string) {
+  private canBeScheduled(taskId: string): boolean {
-    return this.taskGraph.dependencies[taskId].every((id) =>
+    const hasDependenciesCompleted = this.taskGraph.dependencies[taskId].every(
-      this.completedTasks.has(id)
+      (id) => this.completedTasks.has(id)
     );
+
+    // if dependencies have not completed, cannot schedule
+    if (!hasDependenciesCompleted) {
+      return false;
+    }
+
+    // if there are no running tasks, can schedule anything
+    if (this.runningTasks.size === 0) {
+      return true;
+    }
+
+    const runningTasksNotSupportParallelism = Array.from(
+      this.runningTasks
+    ).some((taskId) => {
+      return this.taskGraph.tasks[taskId].parallelism === false;
+    });
+    if (runningTasksNotSupportParallelism) {
+      // if any running tasks do not support parallelism, no other tasks can be scheduled
+      return false;
+    } else {
+      // if all running tasks support parallelism, can only schedule task with parallelism
+      return this.taskGraph.tasks[taskId].parallelism === true;
+    }
   }
 }

packages/playwright/src/plugins/plugin.spec.ts

@@ -91,6 +91,7 @@ describe('@nx/playwright/plugin', () => {
                     "outputs": [
                       "{projectRoot}/test-results",
                     ],
+                    "parallelism": false,
                   },
                   "e2e-ci": {
                     "cache": true,
@@ -123,6 +124,7 @@ describe('@nx/playwright/plugin', () => {
                     "outputs": [
                       "{projectRoot}/test-results",
                     ],
+                    "parallelism": false,
                   },
                 },
               },
@@ -200,6 +202,7 @@ describe('@nx/playwright/plugin', () => {
                       "{projectRoot}/test-results/html",
                       "{projectRoot}/test-results",
                     ],
+                    "parallelism": false,
                   },
                   "e2e-ci": {
                     "cache": true,
@@ -235,6 +238,7 @@ describe('@nx/playwright/plugin', () => {
                       "{projectRoot}/test-results/html",
                       "{projectRoot}/test-results",
                     ],
+                    "parallelism": false,
                   },
                 },
               },
@@ -323,6 +327,7 @@ describe('@nx/playwright/plugin', () => {
         "outputs": [
           "{projectRoot}/test-results",
         ],
+        "parallelism": false,
       }
     `);
     expect(targets['e2e-ci--tests/run-me.spec.ts']).toMatchInlineSnapshot(`
@@ -358,6 +363,7 @@ describe('@nx/playwright/plugin', () => {
         "outputs": [
           "{projectRoot}/test-results",
         ],
+        "parallelism": false,
       }
     `);
     expect(targets['e2e-ci--tests/run-me-2.spec.ts']).toMatchInlineSnapshot(`
@@ -393,6 +399,7 @@ describe('@nx/playwright/plugin', () => {
         "outputs": [
           "{projectRoot}/test-results",
         ],
+        "parallelism": false,
       }
     `);
     expect(targets['e2e-ci--tests/skip-me.spec.ts']).not.toBeDefined();

packages/playwright/src/plugins/plugin.ts

@@ -162,6 +162,7 @@ async function buildPlaywrightTargets(
     options: {
       cwd: '{projectRoot}',
     },
+    parallelism: false,
     metadata: {
       technologies: ['playwright'],
       description: 'Runs Playwright Tests',
@@ -257,6 +258,7 @@ async function buildPlaywrightTargets(
       inputs: ciBaseTargetConfig.inputs,
       outputs: ciBaseTargetConfig.outputs,
       dependsOn,
+      parallelism: false,
       metadata: {
         technologies: ['playwright'],
         description: 'Runs Playwright Tests in CI',

packages/plugin/src/generators/executor/files/hasher/hasher.spec.ts.template

@@ -14,7 +14,8 @@ describe('<%=propertyName%>Hasher', () => {
                 target: 'target'
             },
             overrides: {},
-            outputs: []
+            outputs: [],
+            parallelism: true
         }, {
             hasher: mockHasher
         } as unknown as HasherContext)