[jira] [Updated] (CASSANDRA-15666) Race condition when completing stream sessions

["ZhaoYang (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CASSANDRA-15666?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

ZhaoYang updated CASSANDRA-15666:
---------------------------------
    Reviewers: Benjamin Lerer, Sergio Bossa  (was: Benjamin Lerer, Sergio Bossa, ZhaoYang)

> Race condition when completing stream sessions
> ----------------------------------------------
>
>                 Key: CASSANDRA-15666
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-15666
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Legacy/Streaming and Messaging
>            Reporter: Sergio Bossa
>            Assignee: ZhaoYang
>            Priority: Normal
>              Labels: pull-request-available
>             Fix For: 4.0, 4.0-alpha5
>
>          Time Spent: 20m
>  Remaining Estimate: 0h
>
> {{StreamSession#prepareAsync()}} executes, as the name implies, asynchronously from the IO thread: this opens up for race conditions between the sending of the {{PrepareSynAckMessage}} and the call to {{StreamSession#maybeCompleted()}}. I.e., the following could happen:
> 1) Node A sends {{PrepareSynAckMessage}} from the {{prepareAsync()}} thread.
> 2) Node B receives it and starts streaming.
> 3) Node A receives the streamed file and sends {{ReceivedMessage}}.
> 4) At this point, if this was the only file to stream, both nodes are ready to close the session via {{maybeCompleted()}}, but:
> a) Node A will call it twice from both the IO thread and the thread at #1, closing the session and its channels.
> b) Node B will attempt to send a {{CompleteMessage}}, but will fail because the session has been closed in the meantime.
> There are other subtle variations of the pattern above, depending on the order of concurrently sent/received messages.
> I believe the best fix would be to modify the message exchange so that:
> 1) Only the "follower" is allowed to send the {{CompleteMessage}}.
> 2) Only the "initiator" is allowed to close the session and its channels after receiving the {{CompleteMessage}}.
> By doing so, the message exchange logic would be easier to reason about, which is overall a win anyway.



--
This message was sent by Atlassian Jira
(v8.3.4#803005)

---------------------------------------------------------------------
To unsubscribe, e-mail: commits-unsubscribe@cassandra.apache.org
For additional commands, e-mail: commits-help@cassandra.apache.org