angela created OAK-3616:
---------------------------
Summary: Reconsider Synchronization with
ContentSessionImpl.checkLive
Key: OAK-3616
URL: https://issues.apache.org/jira/browse/OAK-3616
Project: Jackrabbit Oak
Issue Type: Improvement
Components: core
Reporter: angela
Priority: Minor
while running permission related benchmarks directly on Oak (without the extra
oak-jcr layer), i found a considerable difference between
- concurrent read with a single content session
- concurrent read with different content sessions
according to the built-in profiler information the former seemed to be limited
by the synchronized {{ContentSessionImpl.checkLive}} call:
{code}
# CugOakTest C min 10% 50% 90% max
N
Import deep tree: 8432
All paths: 123545
Oak-Tar 1 15 18 22 25 31
229
Oak-Tar 2 19 25 29 33 38
344
Oak-Tar 4 26 33 39 45 51
513
Oak-Tar 8 70 86 94 102 110
431
Oak-Tar 10 65 105 119 131 143
427
Oak-Tar 15 92 152 169 186 210
449
Oak-Tar 20 148 212 229 250 265
440
Oak-Tar 50 283 485 549 602 666
480
Profiler: top 20 stack trace(s) of 50647 ms:
15517/45026 (34%):
at
org.apache.jackrabbit.oak.core.ContentSessionImpl.checkLive(ContentSessionImpl.java:85)
at org.apache.jackrabbit.oak.core.MutableRoot.checkLive(MutableRoot.java:172)
at org.apache.jackrabbit.oak.core.MutableTree.beforeRead(MutableTree.java:333)
at org.apache.jackrabbit.oak.core.MutableTree.hasProperty(MutableTree.java:133)
at
org.apache.jackrabbit.oak.plugins.tree.TreeLocation$NodeLocation.getChild(TreeLocation.java:166)
at
org.apache.jackrabbit.oak.plugins.tree.TreeLocation.create(TreeLocation.java:62)
at org.apache.jackrabbit.oak.benchmark.CugOakTest.runTest(CugOakTest.java:95)
at
org.apache.jackrabbit.oak.benchmark.AbstractTest.execute(AbstractTest.java:347)
at
org.apache.jackrabbit.oak.benchmark.ReadDeepTreeTest.execute(ReadDeepTreeTest.java:35)
at
org.apache.jackrabbit.oak.benchmark.AbstractTest.execute(AbstractTest.java:356)
at
org.apache.jackrabbit.oak.benchmark.AbstractTest.access$000(AbstractTest.java:45)
at
org.apache.jackrabbit.oak.benchmark.AbstractTest$Executor.run(AbstractTest.java:277)
12279/45026 (27%):
at
org.apache.jackrabbit.oak.core.ContentSessionImpl.checkLive(ContentSessionImpl.java:85)
at org.apache.jackrabbit.oak.core.MutableRoot.checkLive(MutableRoot.java:172)
at org.apache.jackrabbit.oak.core.MutableTree.beforeRead(MutableTree.java:333)
at org.apache.jackrabbit.oak.core.MutableTree.getChild(MutableTree.java:160)
at
org.apache.jackrabbit.oak.plugins.tree.TreeLocation$NodeLocation.getChild(TreeLocation.java:169)
at
org.apache.jackrabbit.oak.plugins.tree.TreeLocation.create(TreeLocation.java:62)
at org.apache.jackrabbit.oak.benchmark.CugOakTest.runTest(CugOakTest.java:95)
at
org.apache.jackrabbit.oak.benchmark.AbstractTest.execute(AbstractTest.java:347)
at
org.apache.jackrabbit.oak.benchmark.ReadDeepTreeTest.execute(ReadDeepTreeTest.java:35)
at
org.apache.jackrabbit.oak.benchmark.AbstractTest.execute(AbstractTest.java:356)
at
org.apache.jackrabbit.oak.benchmark.AbstractTest.access$000(AbstractTest.java:45)
at
org.apache.jackrabbit.oak.benchmark.AbstractTest$Executor.run(AbstractTest.java:277)
3119/45026 (6%):
at
org.apache.jackrabbit.oak.core.ContentSessionImpl.checkLive(ContentSessionImpl.java:85)
at org.apache.jackrabbit.oak.core.MutableRoot.checkLive(MutableRoot.java:172)
at org.apache.jackrabbit.oak.core.MutableTree.beforeRead(MutableTree.java:333)
at org.apache.jackrabbit.oak.core.MutableTree.hasProperty(MutableTree.java:133)
at
org.apache.jackrabbit.oak.plugins.tree.TreeLocation$PropertyLocation.exists(TreeLocation.java:222)
at org.apache.jackrabbit.oak.benchmark.CugOakTest.runTest(CugOakTest.java:96)
at
org.apache.jackrabbit.oak.benchmark.AbstractTest.execute(AbstractTest.java:347)
at
org.apache.jackrabbit.oak.benchmark.ReadDeepTreeTest.execute(ReadDeepTreeTest.java:35)
at
org.apache.jackrabbit.oak.benchmark.AbstractTest.execute(AbstractTest.java:356)
at
org.apache.jackrabbit.oak.benchmark.AbstractTest.access$000(AbstractTest.java:45)
at
org.apache.jackrabbit.oak.benchmark.AbstractTest$Executor.run(AbstractTest.java:277)
1694/45026 (3%):
at
org.apache.jackrabbit.oak.core.ContentSessionImpl.checkLive(ContentSessionImpl.java:85)
at org.apache.jackrabbit.oak.core.MutableRoot.checkLive(MutableRoot.java:172)
at org.apache.jackrabbit.oak.core.MutableRoot.getTree(MutableRoot.java:216)
at org.apache.jackrabbit.oak.core.MutableRoot.getTree(MutableRoot.java:66)
at
org.apache.jackrabbit.oak.plugins.tree.TreeLocation.create(TreeLocation.java:60)
at org.apache.jackrabbit.oak.benchmark.CugOakTest.runTest(CugOakTest.java:95)
at
org.apache.jackrabbit.oak.benchmark.AbstractTest.execute(AbstractTest.java:347)
at
org.apache.jackrabbit.oak.benchmark.ReadDeepTreeTest.execute(ReadDeepTreeTest.java:35)
at
org.apache.jackrabbit.oak.benchmark.AbstractTest.execute(AbstractTest.java:356)
at
org.apache.jackrabbit.oak.benchmark.AbstractTest.access$000(AbstractTest.java:45)
at
org.apache.jackrabbit.oak.benchmark.AbstractTest$Executor.run(AbstractTest.java:277)
1356/45026 (3%):
at
org.apache.jackrabbit.oak.core.ContentSessionImpl.checkLive(ContentSessionImpl.java:85)
at org.apache.jackrabbit.oak.core.MutableRoot.checkLive(MutableRoot.java:172)
at org.apache.jackrabbit.oak.core.MutableTree.beforeRead(MutableTree.java:333)
at org.apache.jackrabbit.oak.core.MutableTree.getProperty(MutableTree.java:127)
at
org.apache.jackrabbit.oak.plugins.tree.TreeLocation$PropertyLocation.getProperty(TreeLocation.java:233)
at org.apache.jackrabbit.oak.benchmark.CugOakTest.runTest(CugOakTest.java:97)
at
org.apache.jackrabbit.oak.benchmark.AbstractTest.execute(AbstractTest.java:347)
at
org.apache.jackrabbit.oak.benchmark.ReadDeepTreeTest.execute(ReadDeepTreeTest.java:35)
at
org.apache.jackrabbit.oak.benchmark.AbstractTest.execute(AbstractTest.java:356)
at
org.apache.jackrabbit.oak.benchmark.AbstractTest.access$000(AbstractTest.java:45)
at
org.apache.jackrabbit.oak.benchmark.AbstractTest$Executor.run(AbstractTest.java:277)
summary:
79%: org.apache.jackrabbit.oak.core
8%: org.apache.jackrabbit.oak.plugins.segment
5%: org.apache.jackrabbit.oak.plugins.memory
{code}
after discussing this with [~mduerig], i tmp made the {{live}} field
{{volatile}} and removed the synchronization. as a result the concurrent random
read with a single session seemed to be improved (in fact showing more or less
the identical figures than when executing the test with concurrent reads of
different sessions:
{code}
# CugOakTest , C, min, 10%, 50%, 90%, max,
N
Oak-Tar , 1, 11, 17, 21, 26, 30,
234
Oak-Tar , 2, 17, 25, 29, 34, 37,
345
Oak-Tar , 4, 34, 39, 43, 47, 51,
465
Oak-Tar , 8, 28, 37, 47, 65, 96,
813
Oak-Tar , 10, 29, 41, 55, 76, 135,
873
Oak-Tar , 15, 27, 48, 80, 127, 220,
894
Oak-Tar , 20, 26, 54, 103, 178, 337,
910
Oak-Tar , 50, 26, 82, 230, 444, 1237,
953
summary:
35%: org.apache.jackrabbit.oak.plugins.segment
13%: org.apache.jackrabbit.oak.plugins.memory
12%: org.apache.jackrabbit.oak.security.authorization.permission
{code}
Should be consider removing the synchronized statement? I am not sure how
important concurrent reads with the same content sessions are, but nevertheless
i was a bit surprised by the numbers.
[~mduerig], what do you think?
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