Feature/quic httpreq init #2
Open
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
jrhee17
pushed a commit
that referenced
this pull request
Nov 1, 2021
…tor (netty#10890) Motivation: A race detector discovered a data race in GlobalEventExecutor present in netty 4.1.51.Final: ``` Write of size 4 at 0x0000cea08774 by thread T103: #0 io.netty.util.internal.DefaultPriorityQueue.poll()Lio/netty/util/internal/PriorityQueueNode; DefaultPriorityQueue.java:113 #1 io.netty.util.internal.DefaultPriorityQueue.poll()Ljava/lang/Object; DefaultPriorityQueue.java:31 #2 java.util.AbstractQueue.remove()Ljava/lang/Object; AbstractQueue.java:113 #3 io.netty.util.concurrent.AbstractScheduledEventExecutor.pollScheduledTask(J)Ljava/lang/Runnable; AbstractScheduledEventExecutor.java:133 #4 io.netty.util.concurrent.GlobalEventExecutor.fetchFromScheduledTaskQueue()V GlobalEventExecutor.java:119 netty#5 io.netty.util.concurrent.GlobalEventExecutor.takeTask()Ljava/lang/Runnable; GlobalEventExecutor.java:106 netty#6 io.netty.util.concurrent.GlobalEventExecutor$TaskRunner.run()V GlobalEventExecutor.java:240 netty#7 io.netty.util.internal.ThreadExecutorMap$2.run()V ThreadExecutorMap.java:74 netty#8 io.netty.util.concurrent.FastThreadLocalRunnable.run()V FastThreadLocalRunnable.java:30 netty#9 java.lang.Thread.run()V Thread.java:835 netty#10 (Generated Stub) <null> Previous read of size 4 at 0x0000cea08774 by thread T110: #0 io.netty.util.internal.DefaultPriorityQueue.size()I DefaultPriorityQueue.java:46 #1 io.netty.util.concurrent.GlobalEventExecutor$TaskRunner.run()V GlobalEventExecutor.java:263 #2 io.netty.util.internal.ThreadExecutorMap$2.run()V ThreadExecutorMap.java:74 #3 io.netty.util.concurrent.FastThreadLocalRunnable.run()V FastThreadLocalRunnable.java:30 #4 java.lang.Thread.run()V Thread.java:835 netty#5 (Generated Stub) <null> ``` The race is legit, but benign. To trigger it requires a TaskRunner to begin exiting and set 'started' to false, more work to be scheduled which starts a new TaskRunner, that work then needs to schedule additional work which modifies 'scheduledTaskQueue', and then the original TaskRunner checks 'scheduledTaskQueue'. But there is no danger to this race as it can only produce a false negative in the condition which causes the code to CAS 'started' which is thread-safe. Modifications: Delete problematic references to scheduledTaskQueue. The only way scheduledTaskQueue could be modified since the last check is if another TaskRunner is running, in which case the current TaskRunner doesn't care. Result: Data-race free code, and a bit less code to boot.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Motivation:
Explain here the context, and why you're making that change.
What is the problem you're trying to solve.
Modification:
Describe the modifications you've done.
Result:
Fixes #.
If there is no issue then describe the changes introduced by this PR.