Record stdout and stderr from the worker. Add a more detailed example

src/services/calc-queue/CalcQueue.js

@@ -1,3 +1,4 @@
+const dotenv = require('dotenv')
 const EventEmitter = require('events')
 const threads = require('worker_threads')
 const path = require('path')
@@ -6,6 +7,8 @@ const fs = require('fs')
 const Exceptions = require('./exceptions.js')
 const CalcTask = require('./CalcTask.js')
 
+dotenv.config()
+
 // Basic utility functions to help the queue manager
 const CalcQueueUtils = {
   getCalcWorker: function(calcFn) {
@@ -28,8 +31,21 @@ const CalcQueueUtils = {
 
     const task = this.queue.shift()
 
-    task._worker = new threads.Worker(task.workerPath())
+    task._worker = new threads.Worker(
+      task.workerPath(),
+      {
+        stderr: true,
+        stdout: true,
+        workerData: { 'id': task._id }
+      }
+    )
 
+    task._worker.stdout.on('data', (chunk) => {
+      task._stdout = task._stdout.concat(chunk)
+    })
+    task._worker.stderr.on('data', (chunk) => {
+      task._stderr = task._stderr.concat(chunk)
+    })
     task._worker.on('message', (msg) => {
       task._messages.push(msg)
     })
@@ -97,8 +113,19 @@ CalcQueue.prototype = {
         'id': q.id(),
         'calcFn': q.calcFn(),
         'result': q.result(),
+        'stdout': q.stdout().trim().split('\n'),
+        'stderr': q.stderr().trim().split('\n'),
         'messages': q.messages(),
-        'error': (q.error() == null ? null : q.error().message)
+        'error': (
+          q.error() == null
+          ? null
+          : q.error().name + ': ' + q.error().message
+        ),
+        'errorStack': (
+          process.env.NODE_ENV !== 'development' || q.error() == null
+          ? null
+          : q.error().stack.split('\n')
+        )
       }
     })
   },

src/services/calc-queue/CalcTask.js

@@ -12,6 +12,8 @@ const CalcTask = function(id, calcFn, workerPath) {
   this._calcFn = calcFn
   this._workerPath = workerPath
   this._result = null
+  this._stderr = ''
+  this._stdout = ''
   this._messages = []
   this._error = null
   this._worker = null
@@ -36,6 +38,12 @@ CalcTask.prototype = {
     return this._result != null
   },
 
+  stdout: function() {
+    return this._stdout
+  },
+  stderr: function() {
+    return this._stderr
+  },
   messages: function() {
     return this._messages
   },

src/workers/example.js

@@ -1,15 +1,57 @@
+const threads = require('worker_threads')
 
-console.log('This is an example worker')
+// Worker task info
+/* maxParallel: [0,1,n] 0 = auto (usually nproc), 1 = single instance,
+ *                      n = max 'n' instances
+ * shareParallel: [true/false] indicates if the worker can be run in parallel
+ *                             with other workers.
+ * usesGPU: [true/false] indicates if the worker requires the GPU
+ */
+const taskInfo = {
+  maxParallel: 0,
+  shareParallel: true,
+  usesGPU: false
+}
 
-new Promise((resolve, reject) => {
+// The task to be run
+const task = function() {
+  console.log('This is an example worker')
+
+  console.log('This is the data from the calling thread:')
+  console.log(threads.workerData)
+
+  threads.parentPort.postMessage('This is a message')
+  threads.parentPort.postMessage({
+    color: 'red',
+    text: '$color is my favourite'
+  })
+
+  new Promise((resolve, reject) => {
     setTimeout((() => {
       console.log('I did something (nothing) for 5 seconds!');
       resolve()
     }).bind(this), 5000)
-})
+  })
+
+  new Promise((resolve, reject) => {
+    setTimeout((() => {
+      console.error('This is an error message after 6 seconds!');
+      resolve()
+    }).bind(this), 6000)
+  })
+
+  new Promise((resolve, reject) => {
+    setTimeout((() => {
+      throw new Error('Exceptions in the worker are logged in the parent')
+    }).bind(this), 7000)
+  })
+}
 
 if (!module.parent) {
-  console.log('not a module')
+  if (!threads.isMainThread) {
+    task()
+  }
 } else {
-  console.log('loaded as a module')
+  module.exports = taskInfo
+  module.task = task
 }