Fixes #5997: The same message may be exported twice to log targets

framework/CHANGELOG.md

@@ -23,6 +23,7 @@ Yii Framework 2 Change Log
 - Bug #5863: Selecting all individual `yii\grid\CheckboxColumn` checkboxes in grid view wasn't resulting in "all" checkbox selected (samdark)
 - Bug #5893: `yii\helpers\ArrayHelper::toArray()` now applies `$properties` parameter for converting descending objects in recursive calls (otsec)
 - Bug #5925: `ArrayHelper::htmlEncode()` does not work properly when the value being encoded is a nested array (tebazil)
+- Bug #5997: The same message may be exported twice to log targets (klimov-paul)
 - Bug: Gii console command help information does not contain global options (qiangxue)
 - Bug: `yii\web\UrlRule` was unable to create URLs for rules containing unicode characters (samdark)
 - Enh #4181: Added `yii\bootstrap\Modal::$headerOptions` and `yii\bootstrap\Modal::$footerOptions` (tuxoff, samdark)

framework/log/Logger.php

@@ -163,7 +163,9 @@ class Logger extends Component
     public function flush($final = false)
     {
         $messages = $this->messages;
-        $this->messages = []; // prevent processing same message twice in case flush is invoked during dispatching
+        // https://github.com/yiisoft/yii2/issues/5619
+        // new messages could be logged while the existing ones are being handled by targets
+        $this->messages = [];
         if ($this->dispatcher instanceof Dispatcher) {
             $this->dispatcher->dispatch($messages, $final);
         }