console: don't attach unnecessary error handlers

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 <[email protected]> Reviewed-By: Ruben Bridgewater <[email protected]> Reviewed-By: Gus Caplan <[email protected]> Reviewed-By: Jeremiah Senkpiel <[email protected]> Reviewed-By: Rich Trott <[email protected]> Reviewed-By: Trivikram Kamat <[email protected]>
nodejs · May 17, 2019 · da102cd · da102cd
1 parent 6984ca1
commit da102cd
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Showing 2 changed files with 18 additions and 1 deletion.
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.
+    }));
+  }
+}