[jira] [Resolved] (CASSANDRA-5830) Paxos loops endlessly due to faulty condition check

["Jonathan Ellis (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CASSANDRA-5830?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jonathan Ellis resolved CASSANDRA-5830.
---------------------------------------

    Resolution: Fixed
      Reviewer: jbellis
      Assignee: Soumava Ghosh

Fixed condition check in 4b4ccc3ccfcc7be8fad0b25bde9a180f0016d520, thanks!
                
> Paxos loops endlessly due to faulty condition check
> ---------------------------------------------------
>
>                 Key: CASSANDRA-5830
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-5830
>             Project: Cassandra
>          Issue Type: Bug
>    Affects Versions: 2.0 beta 2
>            Reporter: Soumava Ghosh
>            Assignee: Soumava Ghosh
>              Labels: paxos
>             Fix For: 2.0
>
>
> Following is the code segment (StorageProxy.java:361) which causes the issue: 
> Start is the start time of the paxos, is always less than the current system time, and therefore the negative difference is always less than the timeout. 
> {code:title=StorageProxy.java|borderStyle=solid}
> private static UUID beginAndRepairPaxos(long start, ByteBuffer key, CFMetaData metadata, List<InetAddress> liveEndpoints, int requiredParticipants, ConsistencyLevel consistencyForPaxos)
>     throws WriteTimeoutException
>     {
>         long timeout = TimeUnit.MILLISECONDS.toNanos(DatabaseDescriptor.getCasContentionTimeout());
>         PrepareCallback summary = null;
>         while (start - System.nanoTime() < timeout)
>         {
>             long ballotMillis = summary == null
>                               ? System.currentTimeMillis()
>                               : Math.max(System.currentTimeMillis(), 1 + UUIDGen.unixTimestamp(summary.inProgressCommit.ballot));
>             UUID ballot = UUIDGen.getTimeUUID(ballotMillis);
> {code}
> Here, the paxos gets stuck when PREPARE returns 'true' but with inProgressCommit. The code in StorageProxy.java:beginAndRepairPaxos() then tries to issue a PROPOSE and COMMIT for the inProgressCommit, and if it repeatedly receives 'false' as a PREPARE_RESPONSE it gets stuck in an endless loop until PREPARE_RESPONSE is true. 

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