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From "Romain Hardouin (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-11363) High Blocked NTR When Connecting
Date Fri, 05 Aug 2016 17:10:21 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-11363?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15409734#comment-15409734
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Romain Hardouin commented on CASSANDRA-11363:
---------------------------------------------

I see a lower NTR blocked percentage with 1024 max queued requests.
 
I attached `max_queued_ntr_property.txt` to set this value in `cassandra-env.sh` and it turns
out that 1536 was a good value in my case. I don't see any blocked NTR so far. That said it's
just a workaround because the root cause might be elsewhere. Anyway I think it's better to
have a property to set this value instead of a hard coded number. WDYT?

> High Blocked NTR When Connecting
> --------------------------------
>
>                 Key: CASSANDRA-11363
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-11363
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Coordination
>            Reporter: Russell Bradberry
>            Assignee: Paulo Motta
>         Attachments: cassandra-102-cms.stack, cassandra-102-g1gc.stack, max_queued_ntr_property.txt,
thread-queue-2.1.txt
>
>
> When upgrading from 2.1.9 to 2.1.13, we are witnessing an issue where the machine load
increases to very high levels (> 120 on an 8 core machine) and native transport requests
get blocked in tpstats.
> I was able to reproduce this in both CMS and G1GC as well as on JVM 7 and 8.
> The issue does not seem to affect the nodes running 2.1.9.
> The issue seems to coincide with the number of connections OR the number of total requests
being processed at a given time (as the latter increases with the former in our system)
> Currently there is between 600 and 800 client connections on each machine and each machine
is handling roughly 2000-3000 client requests per second.
> Disabling the binary protocol fixes the issue for this node but isn't a viable option
cluster-wide.
> Here is the output from tpstats:
> {code}
> Pool Name                    Active   Pending      Completed   Blocked  All time blocked
> MutationStage                     0         8        8387821         0              
  0
> ReadStage                         0         0         355860         0              
  0
> RequestResponseStage              0         7        2532457         0              
  0
> ReadRepairStage                   0         0            150         0              
  0
> CounterMutationStage             32       104         897560         0              
  0
> MiscStage                         0         0              0         0              
  0
> HintedHandoff                     0         0             65         0              
  0
> GossipStage                       0         0           2338         0              
  0
> CacheCleanupExecutor              0         0              0         0              
  0
> InternalResponseStage             0         0              0         0              
  0
> CommitLogArchiver                 0         0              0         0              
  0
> CompactionExecutor                2       190            474         0              
  0
> ValidationExecutor                0         0              0         0              
  0
> MigrationStage                    0         0             10         0              
  0
> AntiEntropyStage                  0         0              0         0              
  0
> PendingRangeCalculator            0         0            310         0              
  0
> Sampler                           0         0              0         0              
  0
> MemtableFlushWriter               1        10             94         0              
  0
> MemtablePostFlush                 1        34            257         0              
  0
> MemtableReclaimMemory             0         0             94         0              
  0
> Native-Transport-Requests       128       156         387957        16            278451
> Message type           Dropped
> READ                         0
> RANGE_SLICE                  0
> _TRACE                       0
> MUTATION                     0
> COUNTER_MUTATION             0
> BINARY                       0
> REQUEST_RESPONSE             0
> PAGED_RANGE                  0
> READ_REPAIR                  0
> {code}
> Attached is the jstack output for both CMS and G1GC.
> Flight recordings are here:
> https://s3.amazonaws.com/simple-logs/cassandra-102-cms.jfr
> https://s3.amazonaws.com/simple-logs/cassandra-102-g1gc.jfr
> It is interesting to note that while the flight recording was taking place, the load
on the machine went back to healthy, and when the flight recording finished the load went
back to > 100.



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