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https://issues.apache.org/jira/browse/CASSANDRA-16714?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Aleksandr Sorokoumov updated CASSANDRA-16714:
---------------------------------------------
Test and Documentation Plan:
{{SlidingTimeRateTest}} fails if the executor runs with a higher thread count,
and the run is lucky enough to get a near-uniform work distribution.
I was able to reproduce the issue by decreasing {{updates}} to 10000 and adding
a sleep statement after {{rate.update(1)}}:
{noformat}
executor.submit(() -> {
threadCnt.computeIfAbsent(Thread.currentThread().getId(), (n)
-> new AtomicInteger())
.incrementAndGet();
time.sleep(1, TimeUnit.MILLISECONDS);
rate.update(1);
try
{
Thread.sleep(2);
}
catch (InterruptedException ie) {}
});
{noformat}
In the snippet above I've also added a per-thread increment to measure work
distribution. The results are:
Without sleep (test passes):
{noformat}
{16=1752, 17=1441, 18=420, 19=1434, 20=468, 21=1259, 22=582, 23=568, 24=670,
13=387, 14=508, 15=511}
{noformat}
With sleep (test fails):
{noformat}
{16=833, 17=834, 18=835, 19=833, 20=833, 21=833, 22=833, 23=833, 24=834,
13=833, 14=833, 15=833}
{noformat}
As a result of the uniform work distribution, concurrent updates hit same
timestamp more frequently which in turn makes the test run quicker in
{{TestTimeSource}} terms with more hits per timestamp.
I suggest to set thread pool size to, say, 4 as well as to increase tolerated
delta to 150. The former will limit the impact of the work distribution effect
while the latter sets more realistic boundaries on the possible values
([patch|https://github.com/apache/cassandra/compare/trunk...Gerrrr:16714-3.11?expand=1]).
Status: Patch Available (was: In Progress)
> Fix org.apache.cassandra.utils.SlidingTimeRateTest.testConcurrentUpdateAndGet
> -----------------------------------------------------------------------------
>
> Key: CASSANDRA-16714
> URL: https://issues.apache.org/jira/browse/CASSANDRA-16714
> Project: Cassandra
> Issue Type: Bug
> Components: Test/unit
> Reporter: Ekaterina Dimitrova
> Assignee: Aleksandr Sorokoumov
> Priority: Normal
> Fix For: 3.11.x
>
>
> Fix org.apache.cassandra.utils.SlidingTimeRateTest.testConcurrentUpdateAndGet
> in Cassandra 3.11
> [https://jenkins-cm4.apache.org/job/Cassandra-3.11/174/testReport/junit/org.apache.cassandra.utils/SlidingTimeRateTest/testConcurrentUpdateAndGet_cdc/]
> We should also propagate the fix to 4.0 where the utility class and the tests
> also exist but they are not currently in use so to remove the noise the tests
> are currently skipped from running at the moment. For reference -
> CASSANDRA-16713
>
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