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https://issues.apache.org/jira/browse/POOL-75?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Takayuki Kaneko updated POOL-75:
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Attachment: ctest.fairness.png
ctest.original.png
java.patch
Hi,
I made the patch of fairness connection pool for trunk.
I ran tests with following settings.
- maxActive = 100
- each thread holds connection for 10 ms
- 300 threads runs cuncurrently
I got the good record of this patch.
dbcptype, throughput, Ave., Var., S.D. , min., 50%, 60%, 70%, 80%, 90%,
max.
----------------------------------------------------------------------------------
original, 8533.9, 35.27, 18488.62, 135.97, 10, 12, 12, 12, 12, 13,
3527
fairness, 8744.2, 34.43, 18.87, 4.34, 10, 34, 34, 34, 35, 36,
160
"original" has a problem about fairness. maximum time of getting connection is
3527 ms
regardless of each threads holds connection for 10 ms.
I put 2 graphs that showed response time of borrowObject.
> [pool] GenericObjectPool not FIFO with respect to borrowing threads
> -------------------------------------------------------------------
>
> Key: POOL-75
> URL: https://issues.apache.org/jira/browse/POOL-75
> Project: Commons Pool
> Issue Type: Improvement
> Affects Versions: Nightly Builds
> Environment: Operating System: All
> Platform: All
> Reporter: Gordon Mohr
> Priority: Minor
> Fix For: 2.0
>
> Attachments: adult-sex.html, ctest.fairness.png, ctest.original.png,
> java.patch
>
>
> GenericObjectPool has recently been made FIFO with respect to the managed pool
> objects -- however, it is still not FIFO with respect to threads requesting
> those objects. Specifically, because standard non-fair Java synchronization
> monitors are used, later threads may barge ahead of earlier threads that are
> already waiting for a pool object to become available. At its extreme, some
> threads can cycle objects through the pool many times while others wait
> interminable.
> Not every application needs FIFO fairness with respect to threads, and such
> fairness implies an overhead, so it need not be the default behavior, but it
> would be a valuable option where many threads are sharing a smaller number of
> pool objects.
> I can submit a FairGenericObjectPool which achieves thread-fairness; it only
> requires small changes to GenericObjectPool which allow some subclass
> overriding.
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