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From Sebastian Estevez <sebastian.este...@datastax.com>
Subject Re: Cassandra stalls and dropped messages not due to GC
Date Fri, 30 Oct 2015 03:06:38 GMT
The thing about the CASSANDRA-9504 theory is that it was solved in 2.1.6
and Jeff's running 2.1.11.

@Jeff

How often does this happen? Can you watch ttop as soon as you notice
increased read/write latencies?

wget
> https://bintray.com/artifact/download/aragozin/generic/sjk-plus-0.3.6.jar
> java -jar sjk-plus-0.3.6.jar ttop -s localhost:7199 -n 30 -o CPU


This should at least tell you which Cassandra threads are causing high
memory allocations  and CPU consumption.

All the best,


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Sebastián Estévez

Solutions Architect | 954 905 8615 | sebastian.estevez@datastax.com

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On Thu, Oct 29, 2015 at 9:36 PM, Graham Sanderson <graham@vast.com> wrote:

> you didn’t say what you upgraded from, but if it is 2.0.x, then look at
> CASSANDRA-9504
>
> If so and you use
>
> commitlog_sync: batch
>
> Then you probably want to set
>
> commitlog_sync_batch_window_in_ms: 1 (or 2)
>
> Note I’m only slightly convinced this is the cause because of your
> READ_REPAIR issues (though if you are dropping a lot of MUTATIONS under
> load and your machines are overloaded, you’d be doing more READ_REPAIR than
> usual probably)
>
> On Oct 29, 2015, at 8:12 PM, Jeff Ferland <jbf@tubularlabs.com> wrote:
>
> Using DSE 4.8.1 / 2.1.11.872, Java version 1.8.0_66
>
> We upgraded our cluster this weekend and have been having issues with
> dropped mutations since then. Intensely investigating a single node and
> toying with settings has revealed that GC stalls don’t make up enough time
> to explain the 10 seconds of apparent stall that would cause a hangup.
>
> tpstats output typically shows active threads in the low single digits and
> pending similar or 0. Before a failure, pending MutationStage will
> skyrocket into 5+ digits. System.log regularly shows the gossiper
> complaining, then slow log complaints, then logs dropped mutations.
>
> For the entire minute of 00:55, the gc logging shows no single pause > .14
> seconds and most of them much smaller. Abbreviated GC log after switching
> to g1gc (problem also exhibited before G1GC):
>
> 2015-10-30T00:55:00.550+0000: 6752.857: [GC pause (G1 Evacuation Pause)
> (young)
> 2015-10-30T00:55:02.843+0000: 6755.150: [GC pause (GCLocker Initiated GC)
> (young)
> 2015-10-30T00:55:05.241+0000: 6757.548: [GC pause (G1 Evacuation Pause)
> (young)
> 2015-10-30T00:55:07.755+0000: 6760.062: [GC pause (G1 Evacuation Pause)
> (young)
> 2015-10-30T00:55:10.532+0000: 6762.839: [GC pause (G1 Evacuation Pause)
> (young)
> 2015-10-30T00:55:13.080+0000: 6765.387: [GC pause (G1 Evacuation Pause)
> (young)
> 2015-10-30T00:55:15.914+0000: 6768.221: [GC pause (G1 Evacuation Pause)
> (young)
> 2015-10-30T00:55:18.619+0000: 6770.926: [GC pause (GCLocker Initiated GC)
> (young)
> 2015-10-30T00:55:23.270+0000: 6775.578: [GC pause (GCLocker Initiated GC)
> (young)
> 2015-10-30T00:55:28.662+0000: 6780.969: [GC pause (GCLocker Initiated GC)
> (young)
> 2015-10-30T00:55:33.326+0000: 6785.633: [GC pause (G1 Evacuation Pause)
> (young)
> 2015-10-30T00:55:36.600+0000: 6788.907: [GC pause (G1 Evacuation Pause)
> (young)
> 2015-10-30T00:55:40.050+0000: 6792.357: [GC pause (G1 Evacuation Pause)
> (young)
> 2015-10-30T00:55:43.728+0000: 6796.035: [GC pause (G1 Evacuation Pause)
> (young)
> 2015-10-30T00:55:48.216+0000: 6800.523: [GC pause (G1 Evacuation Pause)
> (young)
> 2015-10-30T00:55:53.621+0000: 6805.928: [GC pause (G1 Evacuation Pause)
> (young)
> 2015-10-30T00:55:59.048+0000: 6811.355: [GC pause (GCLocker Initiated GC)
> (young)
>
> System log snippet of the pattern I’m seeing:
>
> WARN  [GossipTasks:1] 2015-10-30 00:55:25,129  Gossiper.java:747 - Gossip
> stage has 1 pending tasks; skipping status check (no nodes will be marked
> down)
> INFO  [CompactionExecutor:210] 2015-10-30 00:55:26,006
>  CompactionTask.java:141 - Compacting
> [SSTableReader(path='/mnt/cassandra/data/system/hints/system-hints-ka-8283-Data.db'),
> SSTableReader(path='/mnt/cassandra/data/system/hints/system-hints-ka-8286-Data.db'),
> SSTableReader(path='/mnt/cassandra/data/system/hints/system-hints-ka-8284-Data.db'),
> SSTableReader(path='/mnt/cassandra/data/system/hints/system-hints-ka-8285-Data.db'),
> SSTableReader(path='/mnt/cassandra/data/system/hints/system-hints-ka-8287-Data.db')]
> WARN  [GossipTasks:1] 2015-10-30 00:55:26,230  Gossiper.java:747 - Gossip
> stage has 3 pending tasks; skipping status check (no nodes will be marked
> down)
> WARN  [GossipTasks:1] 2015-10-30 00:55:27,330  Gossiper.java:747 - Gossip
> stage has 5 pending tasks; skipping status check (no nodes will be marked
> down)
> WARN  [GossipTasks:1] 2015-10-30 00:55:28,431  Gossiper.java:747 - Gossip
> stage has 7 pending tasks; skipping status check (no nodes will be marked
> down)
> WARN  [GossipTasks:1] 2015-10-30 00:55:29,531  Gossiper.java:747 - Gossip
> stage has 10 pending tasks; skipping status check (no nodes will be marked
> down)
> INFO  [CqlSlowLog-Writer-thread-0] 2015-10-30 00:55:32,448
>  CqlSlowLogWriter.java:151 - Recording statements with duration of 16042 in
> slow log
> INFO  [CqlSlowLog-Writer-thread-0] 2015-10-30 00:55:32,451
>  CqlSlowLogWriter.java:151 - Recording statements with duration of 16047 in
> slow log
> INFO  [CqlSlowLog-Writer-thread-0] 2015-10-30 00:55:32,453
>  CqlSlowLogWriter.java:151 - Recording statements with duration of 16018 in
> slow log
> INFO  [CqlSlowLog-Writer-thread-0] 2015-10-30 00:55:32,454
>  CqlSlowLogWriter.java:151 - Recording statements with duration of 16042 in
> slow log
> INFO  [CqlSlowLog-Writer-thread-0] 2015-10-30 00:55:32,455
>  CqlSlowLogWriter.java:151 - Recording statements with duration of 16024 in
> slow log
> INFO  [CqlSlowLog-Writer-thread-0] 2015-10-30 00:55:32,457
>  CqlSlowLogWriter.java:151 - Recording statements with duration of 16045 in
> slow log
> INFO  [CqlSlowLog-Writer-thread-0] 2015-10-30 00:55:32,458
>  CqlSlowLogWriter.java:151 - Recording statements with duration of 16041 in
> slow log
> INFO  [CqlSlowLog-Writer-thread-0] 2015-10-30 00:55:32,459
>  CqlSlowLogWriter.java:151 - Recording statements with duration of 16040 in
> slow log
> INFO  [CqlSlowLog-Writer-thread-0] 2015-10-30 00:55:32,461
>  CqlSlowLogWriter.java:151 - Recording statements with duration of 16037 in
> slow log
> WARN  [GossipTasks:1] 2015-10-30 00:55:32,697  FailureDetector.java:257 -
> Not marking nodes down due to local pause of 8668629909 > 5000000000
> INFO  [CompactionExecutor:212] 2015-10-30 00:55:32,864
>  ColumnFamilyStore.java:900 - Enqueuing flush of compactions_in_progress:
> 164 (0%) on-heap, 0 (0%) off-heap
> INFO  [MemtableFlushWriter:846] 2015-10-30 00:55:32,865  Memtable.java:347
> - Writing Memtable-compactions_in_progress@969357824(0.008KiB serialized
> bytes, 1 ops, 0%/0% of on/off-heap limit)
> INFO  [MemtableFlushWriter:846] 2015-10-30 00:55:32,865  Memtable.java:382
> - Completed flushing
> /mnt/cassandra/data/system/compactions_in_progress/system-compactions_in_progress-tmp-ka-1461769-Data.db
> (0.000KiB) for commitlog position ReplayPosition(segmentId=1446159752729,
> position=8699402)
> INFO  [ScheduledTasks:1] 2015-10-30 00:55:35,346
>  MessagingService.java:930 - MUTATION messages were dropped in last 5000
> ms: 67432 for internal timeout and 0 for cross node timeout
> INFO  [ScheduledTasks:1] 2015-10-30 00:55:35,350
>  MessagingService.java:930 - READ_REPAIR messages were dropped in last 5000
> ms: 209 for internal timeout and 0 for cross node timeout
>
> I’m starting to suspect I’ll have to take regular stack dumps and catch a
> bad moment, but I figured I’d reach out here before going down that road to
> see if somebody else had ever experienced a similar kind of pain.
>
> -Jeff
>
>
>

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