[
https://issues.apache.org/jira/browse/BOOKKEEPER-215?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13259385#comment-13259385
]
Sijie Guo commented on BOOKKEEPER-215:
--------------------------------------
sure, the code change in bookkeeper persistence manager is to put the
asyncReadEntries in opQueue instead of calling asyncReadEntries directly in the
callback.
{code}
}
}
- startReadingFrom(imlr.startSeqIdIncluded +
entry.getEntryId() + 1);
-
+ // continue scanning messages
+ scanMessages(request, imlr.startSeqIdIncluded +
entry.getEntryId() + 1);
}
}, request.ctx);
}
{code}
the detail code change is as above. it call scanMessages, which put a range
scan op again in topic op queue, instead of startReadingFrom. so the
asyncReadEntries would be executed only the range op is executed, which is in
hedwig thread not in bookkeeper thread.
> Deadlock occurs under high load
> -------------------------------
>
> Key: BOOKKEEPER-215
> URL: https://issues.apache.org/jira/browse/BOOKKEEPER-215
> Project: Bookkeeper
> Issue Type: Bug
> Components: hedwig-server
> Affects Versions: 4.1.0
> Reporter: Aniruddha
> Assignee: Sijie Guo
> Priority: Critical
> Fix For: 4.1.0
>
> Attachments: BK-215.patch, BK-215.patch_v2, hedwig_ts.log
>
>
> LedgerHandle uses a Semaphore(opCounterSem) with a default value of 5000
> permits to implement throttling for outstanding requests. This is causing a
> deadlock under high load. What I've observed is the following - There are a
> fixed number of threads created by OrderedSafeExecutor(mainWorkerPool in
> BookKeeper) and this is used to execute operations by PerChannelBookieClient.
> Under high load, the bookies are not able to satisfy requests at the rate at
> which they are being generated. This exhausts all permits in the Semaphore
> and any further operations block on lh.opCounterSem.acquire(). In this
> scenario, if the connection to the bookies is shut down, channelDisconnected
> in PerChannelBookieClient tries to error out all outstanding entries. The
> errorOutReadKey and errorOutAddKey functions enqueue these operations in the
> same mainWorkerPool, all threads in which are blocked on acquire. So,
> handleBookieFailure is never executed and the server stops responding.
> Blocking operations in a fixed size thread pool doesn't sound quite right.
> Temporarily, I fixed this by having another ExecutorService for every
> PerChannelBookieClient and queuing the operations from the errorOut*
> functions in it, but this is just a quick fix. I feel that the server
> shouldn't rely on LedgerHandle to throttle connections, but do this itself.
> Any other ideas on how to fix this? I'd be happy to contribute a patch.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators:
https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira
