feat: add reload handler flag

README.md

@@ -133,6 +133,7 @@ All CLI options are optional:
 --noTimeout             -t  Disables the timeout feature.
 --prefix                -p  Adds a prefix to every path, to send your requests to http://localhost:3000/[prefix]/[your_path] instead. Default: ''
 --printOutput               Turns on logging of your lambda outputs in the terminal.
+--reloadHandler             Reloads handler with each request.
 --resourceRoutes            Turns on loading of your HTTP proxy settings from serverless.yml
 --useChildProcesses         Run handlers in a child process
 --useDocker                 Run handlers in a docker container.

src/config/commandOptions.js

@@ -118,6 +118,10 @@ export default {
     type: 'boolean',
     usage: 'Outputs your lambda response to the terminal.',
   },
+  reloadHandler: {
+    type: 'boolean',
+    usage: 'Reloads handler with each request.',
+  },
   resourceRoutes: {
     type: 'boolean',
     usage: 'Turns on loading of your HTTP proxy settings from serverless.yml.',

src/config/defaultOptions.js

@@ -26,6 +26,7 @@ export default {
   noTimeout: false,
   prefix: '',
   printOutput: false,
+  reloadHandler: false,
   resourceRoutes: false,
   useChildProcesses: false,
   useDocker: false,

src/lambda/LambdaFunctionPool.js

@@ -84,13 +84,15 @@ export default class LambdaFunctionPool {
       return lambdaFunction
     }
 
-    // find any IDLE
-    lambdaFunction = Array.from(lambdaFunctions).find(
-      ({ status }) => status === 'IDLE',
-    )
+    if (!this.#options.reloadHandler) {
+      // find any IDLE
+      lambdaFunction = Array.from(lambdaFunctions).find(
+        ({ status }) => status === 'IDLE',
+      )
 
-    if (lambdaFunction != null) {
-      return lambdaFunction
+      if (lambdaFunction != null) {
+        return lambdaFunction
+      }
     }
 
     // we don't have any IDLE instances

tests/lambda-run-mode/worker-threads/reload-handler/reload-handler.test.js

@@ -0,0 +1,51 @@
+import assert from 'node:assert'
+import { dirname, resolve } from 'node:path'
+import { env } from 'node:process'
+import { fileURLToPath } from 'node:url'
+import { promisify } from 'node:util'
+import {
+  joinUrl,
+  setup,
+  teardown,
+} from '../../../integration/_testHelpers/index.js'
+
+const setTimeoutPromise = promisify(setTimeout)
+
+const __dirname = dirname(fileURLToPath(import.meta.url))
+
+describe.only('run mode with worker threads', function desc() {
+  beforeEach(() =>
+    setup({
+      servicePath: resolve(__dirname),
+    }),
+  )
+
+  afterEach(() => teardown())
+
+  it('should always create a new lambda instance', async () => {
+    const url = joinUrl(env.TEST_BASE_URL, 'dev/foo')
+
+    const results = []
+
+    // eslint-disable-next-line no-unused-vars
+    for (const _ of Array(100)) {
+      // eslint-disable-next-line no-await-in-loop
+      await setTimeoutPromise(10)
+      results.push(fetch(url))
+    }
+
+    const responses = await Promise.all(results)
+
+    responses.forEach((response) => {
+      assert.equal(response.status, 200)
+    })
+
+    const jsons = await Promise.all(
+      responses.map((response) => response.json()),
+    )
+
+    jsons.forEach((json) => {
+      assert.deepEqual(json, 1)
+    })
+  })
+})

tests/lambda-run-mode/worker-threads/reload-handler/serverless.yml

@@ -0,0 +1,26 @@
+service: run-mode-tests
+
+configValidationMode: error
+
+plugins:
+  - ../../../../
+
+custom:
+  serverless-offline:
+    reloadHandler: true
+
+provider:
+  memorySize: 128
+  name: aws
+  region: us-east-1 # default
+  runtime: nodejs16.x
+  stage: dev
+  versionFunctions: false
+
+functions:
+  foo:
+    events:
+      - http:
+          method: get
+          path: foo
+    handler: src/handler.foo

tests/lambda-run-mode/worker-threads/reload-handler/src/handler.js

@@ -0,0 +1,14 @@
+'use strict'
+
+const { stringify } = JSON
+
+let counter = 0
+
+exports.foo = async function foo() {
+  counter += 1
+
+  return {
+    body: stringify(counter),
+    statusCode: 200,
+  }
+}

tests/lambda-run-mode/worker-threads/reload-handler/src/package.json

@@ -0,0 +1,3 @@
+{
+  "type": "commonjs"
+}