refactor: rename vm to experimental-vm-threads

packages/vitest/src/node/cli-api.ts

@@ -56,6 +56,9 @@ export async function startVitest(
   if (typeof options.browser === 'object' && !('enabled' in options.browser))
     options.browser.enabled = true
 
+  if ('threads' in options && options.experimentalVmThreads)
+    throw new Error('Cannot use both "threads" (or "no-threads") and "experimentalVmThreads" at the same time.')
+
   const ctx = await createVitest(mode, options, viteOverrides)
 
   if (mode === 'test' && ctx.config.coverage.enabled) {

packages/vitest/src/node/cli.ts

@@ -22,6 +22,7 @@ cli
   .option('--api [api]', 'Serve API, available options: --api.port <port>, --api.host [host] and --api.strictPort')
   .option('--threads', 'Enabled threads (default: true)')
   .option('--single-thread', 'Run tests inside a single thread, requires --threads (default: false)')
+  .option('--experimental-vm-threads', 'Run tests in a worker pool using VM isolation (default: false)')
   .option('--silent', 'Silent console output from tests')
   .option('--hideSkippedTests', 'Hide logs for skipped tests')
   .option('--isolate', 'Isolate environment for each test file (default: true)')

packages/vitest/src/node/pool.ts

@@ -7,7 +7,7 @@ import type { Vitest } from './core'
 import { createChildProcessPool } from './pools/child'
 import { createThreadsPool } from './pools/threads'
 import { createBrowserPool } from './pools/browser'
-import { createVmPool } from './pools/vm'
+import { createVmThreadsPool } from './pools/vm-threads'
 import type { WorkspaceProject } from './workspace'
 
 export type WorkspaceSpec = [project: WorkspaceProject, testFile: string]
@@ -31,12 +31,14 @@ export function createPool(ctx: Vitest): ProcessPool {
     child_process: null,
     threads: null,
     browser: null,
-    vm: null,
+    experimentalVmThreads: null,
   }
 
-  function getDefaultPoolName(project: WorkspaceProject) {
+  function getDefaultPoolName(project: WorkspaceProject): VitestPool {
     if (project.config.browser.enabled)
       return 'browser'
+    if (project.config.experimentalVmThreads)
+      return 'experimentalVmThreads'
     if (project.config.threads)
       return 'threads'
     return 'child_process'
@@ -89,7 +91,7 @@ export function createPool(ctx: Vitest): ProcessPool {
       child_process: [] as WorkspaceSpec[],
       threads: [] as WorkspaceSpec[],
       browser: [] as WorkspaceSpec[],
-      vm: [] as WorkspaceSpec[],
+      experimentalVmThreads: [] as WorkspaceSpec[],
     }
 
     for (const spec of files) {
@@ -106,9 +108,9 @@ export function createPool(ctx: Vitest): ProcessPool {
         return pools.browser.runTests(files, invalidate)
       }
 
-      if (pool === 'vm') {
-        pools.vm ??= createVmPool(ctx, options)
-        return pools.vm.runTests(files, invalidate)
+      if (pool === 'experimentalVmThreads') {
+        pools.experimentalVmThreads ??= createVmThreadsPool(ctx, options)
+        return pools.experimentalVmThreads.runTests(files, invalidate)
       }
 
       if (pool === 'threads') {

packages/vitest/src/node/pools/vm.ts → packages/vitest/src/node/pools/vm-threads.ts

@@ -36,7 +36,7 @@ function createWorkerChannel(project: WorkspaceProject) {
   return { workerPort, port }
 }
 
-export function createVmPool(ctx: Vitest, { execArgv, env }: PoolProcessOptions): ProcessPool {
+export function createVmThreadsPool(ctx: Vitest, { execArgv, env }: PoolProcessOptions): ProcessPool {
   const threadsCount = ctx.config.watch
     ? Math.max(Math.floor(cpus().length / 2), 1)
     : Math.max(cpus().length - 1, 1)
@@ -117,14 +117,6 @@ export function createVmPool(ctx: Vitest, { execArgv, env }: PoolProcessOptions)
         return config
       }
 
-      const workspaceMap = new Map<string, WorkspaceProject[]>()
-      for (const [project, file] of specs) {
-        const workspaceFiles = workspaceMap.get(file) ?? []
-        workspaceFiles.push(project)
-        workspaceMap.set(file, workspaceFiles)
-      }
-
-      // it's possible that project defines a file that is also defined by another project
       const { shard } = ctx.config
 
       if (shard)

packages/vitest/src/types/config.ts

@@ -18,7 +18,7 @@ export type { SequenceHooks, SequenceSetupFiles } from '@vitest/runner'
 export type BuiltinEnvironment = 'node' | 'jsdom' | 'happy-dom' | 'edge-runtime'
 // Record is used, so user can get intellisense for builtin environments, but still allow custom environments
 export type VitestEnvironment = BuiltinEnvironment | (string & Record<never, never>)
-export type VitestPool = 'browser' | 'threads' | 'child_process' | 'vm'
+export type VitestPool = 'browser' | 'threads' | 'child_process' | 'experimentalVmThreads'
 export type CSSModuleScopeStrategy = 'stable' | 'scoped' | 'non-scoped'
 
 export type ApiConfig = Pick<CommonServerOptions, 'port' | 'strictPort' | 'host'>
@@ -251,6 +251,16 @@ export interface InlineConfig {
    */
   outputFile?: string | (Partial<Record<BuiltinReporters, string>> & Record<string, string>)
 
+  /**
+   * Run tests using VM context in a worker pool.
+   *
+   * This makes tests run faster, but VM module is unstable. Your tests might leak memory.
+   */
+  experimentalVmThreads?: boolean
+
+  // TODO: document that "--no-isolate" has no effect on experimentalVmThreads
+  // TODO: workerIdleMemoryLimit for experimentalVmThreads, so they don't leak
+
   /**
    * Enable multi-threading
    *

test/core/vitest.config.ts

@@ -45,7 +45,7 @@ export default defineConfig({
       './test/setup.ts',
     ],
     poolMatchGlobs: [
-      ['**/*', 'vm'],
+      ['**/*', 'experimentalVmThreads'],
     ],
     testNamePattern: '^((?!does not include test that).)*$',
     coverage: {