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https://issues.apache.org/jira/browse/OAK-1471?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13921877#comment-13921877
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Tobias Bocanegra commented on OAK-1471:
---------------------------------------
here's the result on my box before the changes:
{noformat}
Benchmarks: ConcurrentEveryoneACLTest (oak 0.19-SNAPSHOT with everyone cache)
Fixtures: Oak-Tar
Runtime: 5
Num Items: 1000
Concurrency: 1,2,4,8,10,15,20,50
--------------------------------------
Executing benchmarks as admin: false on Oak-Tar
-----------------------------------------------------------
# ConcurrentEveryoneACLTest , C, min, 10%, 50%, 90%, max,
N
Oak-Tar , 1, 11, 12, 13, 14, 19,
391
Oak-Tar , 2, 12, 13, 14, 17, 27,
675
Oak-Tar , 4, 15, 16, 19, 23, 55,
1020
Oak-Tar , 8, 31, 50, 53, 56, 114,
743
Oak-Tar , 10, 56, 66, 70, 76, 142,
708
Oak-Tar , 15, 74, 104, 110, 117, 132,
687
Oak-Tar , 20, 92, 136, 145, 154, 169,
698
Oak-Tar , 50, 156, 353, 384, 411, 476,
670
Executing benchmarks as admin: true on Oak-Tar
-----------------------------------------------------------
# ConcurrentEveryoneACLTest , C, min, 10%, 50%, 90%, max,
N
Oak-Tar , 1, 4, 5, 5, 6, 17,
900
Oak-Tar , 2, 5, 5, 6, 8, 21,
1526
Oak-Tar , 4, 6, 7, 8, 11, 26,
2318
Oak-Tar , 8, 13, 24, 26, 33, 68,
1420
Oak-Tar , 10, 19, 30, 33, 46, 79,
1395
Oak-Tar , 15, 40, 47, 52, 76, 120,
1345
Oak-Tar , 20, 36, 61, 67, 94, 145,
1395
Oak-Tar , 50, 115, 158, 179, 255, 310,
1325
{noformat}
{noformat}
Model Name: MacBook Pro
Model Identifier: MacBookPro10,1
Processor Name: Intel Core i7
Processor Speed: 2.6 GHz
Number of Processors: 1
Total Number of Cores: 4
L2 Cache (per Core): 256 KB
L3 Cache: 6 MB
Memory: 16 GB
{noformat}
> Mod count in permission store requires cluster wide synchronization
> -------------------------------------------------------------------
>
> Key: OAK-1471
> URL: https://issues.apache.org/jira/browse/OAK-1471
> Project: Jackrabbit Oak
> Issue Type: Bug
> Components: core
> Reporter: Marcel Reutegger
> Assignee: Tobias Bocanegra
> Priority: Critical
> Fix For: 0.19
>
>
> The current permission store implementation keeps a mod count property on
> some of the nodes to detect changes and update/invalidate a cache when
> required. In general this introduces a contention point when there are
> concurrent modifications of access control entries for a given user. Those
> concurrent changes may introduce conflicts and commits may have to be retried
> after a rebase. This still works somewhat OK when there is just a single oak
> instance, because both segment and document store implementation will
> eventually fall back to locking and serialize the commits. However, it does
> not work well in a cluster, unless we apply the same locking cluster wide.
> See also discussion here:
> http://markmail.org/message/k64udmgc3ctaqmn2
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