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https://issues.apache.org/jira/browse/RATIS-1923?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17783696#comment-17783696
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Tsz-wo Sze commented on RATIS-1923:
-----------------------------------
The javadoc also said "Some attempted update operations on this map by other
threads may be blocked while computation is in progress, ..." It seems that it
won't drop the computed value.
> Netty: atomic operations require side-effect-free functions
> -----------------------------------------------------------
>
> Key: RATIS-1923
> URL: https://issues.apache.org/jira/browse/RATIS-1923
> Project: Ratis
> Issue Type: Bug
> Components: Netty
> Reporter: Tsz-wo Sze
> Assignee: Tsz-wo Sze
> Priority: Major
> Fix For: 3.0.0
>
> Attachments: for-loop.jpg, screenshot-1.png
>
> Time Spent: 40m
> Remaining Estimate: 0h
>
> - The update methods in AtomicReference run in a loop and may call the update
> function multiple time. The old values created by the update function may be
> discarded without cleaning up. In NettyClientStreamRpc.Connection the connect
> method is not side-effect-free. Although it passes a [MemoizedSupplier to
> getAndUpdate|https://github.com/apache/ratis/blob/47e5b6aa148cfe777fb3b7742154fe6b417ea42a/ratis-netty/src/main/java/org/apache/ratis/netty/client/NettyClientStreamRpc.java#L187-L188],
> it still is possible that a value is supplied but then discarded in the
> AtomicReference loop.
> - Similarly, the computeIfAbsent in ConcurrentHashMap also runs in a loop
> and may call the mapping function multiple times. DataStreamMap is
> implemented using a ConcurrentHashMap. However, [the mapping function is not
> side-effect-free|https://github.com/apache/ratis/blob/47e5b6aa148cfe777fb3b7742154fe6b417ea42a/ratis-netty/src/main/java/org/apache/ratis/netty/server/DataStreamManagement.java#L281-L289]
> although it uses a MemoizedSupplier.
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