bug #28813 Fix for race condition in console output stream write (rudolfratusinski)

nicolas-grekas · nicolas-grekas · commit 0651e7cfb42e · 2018-10-14T11:27:40.000-07:00
This PR was merged into the 2.8 branch. Discussion ---------- Fix for race condition in console output stream write | Q | A | ------------- | --- | Branch? | 2.8 | Bug fix? | yes | New feature? | no | BC breaks? | no | Deprecations? | no | Tests pass? | yes | Fixed tickets | | License | MIT | Doc PR | In high throughput environments writing `message` and `PHP_EOL` separately causes race condition issues, where messages might be written in order - message - message - EOL - EOL instead of - message - EOL - message - EOL An example below is a laravel application log tail of queue workers (multiple app instances writing to the same log file) handled by supervisor. Before: ![ezgif-1-77388f9210cf](https://user-images.githubusercontent.com/2752769/46792349-bec13180-cd75-11e8-8f91-92f05762f964.gif) After: ![ezgif-1-0b839d642644](https://user-images.githubusercontent.com/2752769/46792420-e617fe80-cd75-11e8-9414-4bfc85d9c569.gif) Commits ------- 428dea6 Fix for race condition in console output stream write
diff --git a/src/Symfony/Component/Console/Output/StreamOutput.php b/src/Symfony/Component/Console/Output/StreamOutput.php
@@ -70,7 +70,11 @@ public function getStream()
      */
     protected function doWrite($message, $newline)
     {
-        if (false === @fwrite($this->stream, $message) || ($newline && (false === @fwrite($this->stream, PHP_EOL)))) {
+        if ($newline) {
+            $message .= PHP_EOL;
+        }
+
+        if (false === @fwrite($this->stream, $message)) {
             // should never happen
             throw new RuntimeException('Unable to write output.');
         }

Original file line number	Diff line number	Diff line change
`@@ -70,7 +70,11 @@ public function getStream()`
`70`	`70`	`*/`
`71`	`71`	`protected function doWrite($message, $newline)`
`72`	`72`	`{`
`73`		`- if (false === @fwrite($this->stream, $message) \|\| ($newline && (false === @fwrite($this->stream, PHP_EOL)))) {`
	`73`	`+ if ($newline) {`
	`74`	`+ $message .= PHP_EOL;`
	`75`	`+ }`
	`76`	`+`
	`77`	`+ if (false === @fwrite($this->stream, $message)) {`
`74`	`78`	`// should never happen`
`75`	`79`	`throw new RuntimeException('Unable to write output.');`
`76`	`80`	`}`