[GitHub] [incubator-druid] leventov commented on a change in pull request #8808: use copy-on-write list in InMemoryAppender

[GitBox <gi...@apache.org>]

leventov commented on a change in pull request #8808: use copy-on-write list in InMemoryAppender
URL: https://github.com/apache/incubator-druid/pull/8808#discussion_r342202395
 
 

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 File path: core/src/test/java/org/apache/druid/testing/junit/LoggerCaptureRule.java
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 @@ -78,12 +77,13 @@ public void clearLogEvents()
   {
     static final String NAME = InMemoryAppender.class.getName();
 
-    private final List<LogEvent> logEvents;
+    // need copy-on-write collection for thread safety of iteration and modification concurrently outside of a critical section
 
 Review comment:
   This comment doesn't achieve its goal: to help somebody to see why the enclosing class needs to be thread-safe. With the current comment, in order to do that, the reader (developer) should invoke "Find usages" IDE action and analyze these usages carefully. This is time-consuming. In essence, there should be concurrent access documentation, as described in https://github.com/code-review-checklists/java-concurrency#justify-document.
   
   This comment is also misleading because there are no critical sections in this code.

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