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https://issues.apache.org/jira/browse/HDDS-2324?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16954449#comment-16954449
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Mukul Kumar Singh commented on HDDS-2324:
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cc [~bharat] [~arp] [~hanishakoneru] [~nanda]
> Enhance locking mechanism in OzoneMangaer
> -----------------------------------------
>
> Key: HDDS-2324
> URL: https://issues.apache.org/jira/browse/HDDS-2324
> Project: Hadoop Distributed Data Store
> Issue Type: Bug
> Components: Ozone Manager
> Reporter: Rajesh Balamohan
> Priority: Major
> Labels: performance
> Attachments: om_lock_100_percent_read_benchmark.svg,
> om_lock_reader_and_writer_workload.svg
>
>
> OM has reentrant RW lock. With 100% read or 100% write benchmarks, it works
> out reasonably fine. There is already a ticket to optimize the write codepath
> (as it incurs reading from DB for key checks).
> However, when small amount of write workload (e.g 3-5 threads) is added to
> the running read benchmark, throughput suffers significantly. This is due to
> the fact that the reader threads would get blocked often. I have observed
> around 10x slower throughput (i.e 100% read benchmark was running at 12,000
> TPS and with couple of writer threads added to it, it goes down to 1200-1800
> TPS).
> 1. Instead of single write lock, one option could be good to scale out the
> write lock depending on the number of cores available in the system and
> acquire relevant lock by hashing the key.
> 2. Another option is to explore if we can make use of StampedLocks of JDK
> 8.x, which scales well when multiple readers and writers are there. But it is
> not a reentrant lock. So need to explore whether it can be an option or not.
>
>
>
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