console: don't attach unnecessary error handlers

cjihrig · targos · commit da102cda54aa · 2019-05-17T08:13:33.000+02:00
A noop error handler is attached to the console's stream on write. The handler is then immediately removed after the write. This commit skips adding the error handler if one already exists. PR-URL: #27691 Fixes: #27687 Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de> Reviewed-By: Gus Caplan <me@gus.host> Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com> Reviewed-By: Rich Trott <rtrott@gmail.com> Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
diff --git a/lib/internal/console/constructor.js b/lib/internal/console/constructor.js
@@ -231,7 +231,8 @@ Console.prototype[kWriteToConsole] = function(streamSymbol, string) {
   // handle both situations.
   try {
     // Add and later remove a noop error handler to catch synchronous errors.
-    stream.once('error', noop);
+    if (stream.listenerCount('error') === 0)
+      stream.once('error', noop);
 
     stream.write(string, errorHandler);
   } catch (e) {
diff --git a/test/parallel/test-worker-console-listeners.js b/test/parallel/test-worker-console-listeners.js
@@ -0,0 +1,16 @@
+'use strict';
+const common = require('../common');
+const { Worker, isMainThread } = require('worker_threads');
+const EventEmitter = require('events');
+
+if (isMainThread) {
+  process.on('warning', common.mustNotCall('unexpected warning'));
+
+  for (let i = 0; i < EventEmitter.defaultMaxListeners; ++i) {
+    const worker = new Worker(__filename);
+
+    worker.on('exit', common.mustCall(() => {
+      console.log('a'); // This console.log() is part of the test.
+    }));
+  }
+}
