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https://issues.apache.org/jira/browse/JAMES-3660?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Benoit Tellier closed JAMES-3660.
---------------------------------
    Fix Version/s: 3.7.0
       Resolution: Fixed

> Cassandra mailbox creation unstable when high concurency
> --------------------------------------------------------
>
>                 Key: JAMES-3660
>                 URL: https://issues.apache.org/jira/browse/JAMES-3660
>             Project: James Server
>          Issue Type: Improvement
>            Reporter: Benoit Tellier
>            Priority: Major
>             Fix For: 3.7.0
>
>          Time Spent: 20m
>  Remaining Estimate: 0h
>
> org.apache.james.mailbox.cassandra.CassandraMailboxManagerTest$WithBatchSize.creatingConcurrentlyMailboxesWithSameParentShouldNotFail
> tests is enough to trigger instability on the Apache CI
> https://ci-builds.apache.org/job/james/job/ApacheJames/job/PR-685/1/
> {code:java}
> Error Message
> java.lang.RuntimeException: 
> com.datastax.driver.core.exceptions.ReadTimeoutException: Cassandra timeout 
> during read query at consistency SERIAL (1 responses were required but only 0 
> replica responded)
> Stacktrace
> java.util.concurrent.ExecutionException: java.lang.RuntimeException: 
> com.datastax.driver.core.exceptions.ReadTimeoutException: Cassandra timeout 
> during read query at consistency SERIAL (1 responses were required but only 0 
> replica responded)
> Caused by: java.lang.RuntimeException: 
> com.datastax.driver.core.exceptions.ReadTimeoutException: Cassandra timeout 
> during read query at consistency SERIAL (1 responses were required but only 0 
> replica responded)
> Caused by: com.datastax.driver.core.exceptions.ReadTimeoutException: 
> Cassandra timeout during read query at consistency SERIAL (1 responses were 
> required but only 0 replica responded)
> Caused by: com.datastax.driver.core.exceptions.ReadTimeoutException: 
> Cassandra timeout during read query at consistency SERIAL (1 responses were 
> required but only 0 replica responded)
> Standard Output
> 11:29:54.751 [ERROR] o.a.j.u.c.ConcurrentTestRunner - Error caught during 
> concurrent testing (iteration 0, threadNumber 1)
> com.datastax.driver.core.exceptions.ReadTimeoutException: Cassandra timeout 
> during read query at consistency SERIAL (1 responses were required but only 0 
> replica responded)
>       at com.datastax.driver.core.Responses$Error$1.decode(Responses.java:90)
>       at com.datastax.driver.core.Responses$Error$1.decode(Responses.java:65)
>       at 
> com.datastax.driver.core.Message$ProtocolDecoder.decode(Message.java:297)
>       at 
> com.datastax.driver.core.Message$ProtocolDecoder.decode(Message.java:268)
>       at 
> com.datastax.shaded.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:88)
>       ... 25 common frames omitted
> Wrapped by: com.datastax.driver.core.exceptions.ReadTimeoutException: 
> Cassandra timeout during read query at consistency SERIAL (1 responses were 
> required but only 0 replica responded)
> {code}
> In short, the LWT usage is enough to create contention.
> Looking closer at the issue, StoreMailboxManager does numerous defensive 
> SERIAL reads (doing empty paxos commits) which ends up further degrading 
> performance and increase contention.
> I believe removing these defensive reads would make our code more stable.
> It resulted in faster (x2) test for 
> gConcurrentlyMailboxesWithSameParentShouldNotFail
>  



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