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https://issues.apache.org/jira/browse/SOLR-12833?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16809650#comment-16809650
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Andrzej Bialecki edited comment on SOLR-12833 at 4/4/19 9:26 AM:
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bq. if there is not a lot of competition on same version bucket and the update
usually finishes fast
This sounds like a chicken & egg situation - how would they know the updates
don't compete without actually trying this out?
Also, I'm not very familiar with how these buckets work, so I'm probably
missing something deeper here .. but isn't the {{vinfo.lockForUpdate()}}, which
is always called before we try to lock the bucket, sufficient for
synchronization? Basically this already guarantees that no two threads will
execute concurrently the same sections in {{versionAdd}} and {{versionDelete}}.
Edit: also, I don't think there are any unit tests that actually demonstrate
the issue this change was meant to fix?
was (Author: ab):
bq. if there is not a lot of competition on same version bucket and the update
usually finishes fast
This sounds like a chicken & egg situation - how would they know the updates
don't compete without actually trying this out?
Also, I'm not very familiar with how these buckets work, so I'm probably
missing something deeper here .. but isn't the {{vinfo.lockForUpdate()}}, which
is always called before we try to lock the bucket, sufficient for
synchronization? Basically this already guarantees that no two threads will
execute concurrently the same sections in {{versionAdd}} and {{versionDelete}}.
> Use timed-out lock in DistributedUpdateProcessor
> ------------------------------------------------
>
> Key: SOLR-12833
> URL: https://issues.apache.org/jira/browse/SOLR-12833
> Project: Solr
> Issue Type: Improvement
> Security Level: Public(Default Security Level. Issues are Public)
> Components: update, UpdateRequestProcessors
> Affects Versions: 7.5, 8.0
> Reporter: jefferyyuan
> Assignee: Mark Miller
> Priority: Minor
> Fix For: 7.7, 8.0
>
> Attachments: SOLR-12833-noint.patch, SOLR-12833.patch,
> SOLR-12833.patch
>
> Time Spent: 20m
> Remaining Estimate: 0h
>
> There is a synchronize block that blocks other update requests whose IDs fall
> in the same hash bucket. The update waits forever until it gets the lock at
> the synchronize block, this can be a problem in some cases.
>
> Some add/update requests (for example updates with spatial/shape analysis)
> like may take time (30+ seconds or even more), this would the request time
> out and fail.
> Client may retry the same requests multiple times or several minutes, this
> would make things worse.
> The server side receives all the update requests but all except one can do
> nothing, have to wait there. This wastes precious memory and cpu resource.
> We have seen the case 2000+ threads are blocking at the synchronize lock, and
> only a few updates are making progress. Each thread takes 3+ mb memory which
> causes OOM.
> Also if the update can't get the lock in expected time range, its better to
> fail fast.
>
> We can have one configuration in solrconfig.xml:
> updateHandler/versionLock/timeInMill, so users can specify how long they want
> to wait the version bucket lock.
> The default value can be -1, so it behaves same - wait forever until it gets
> the lock.
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