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From "Vadim Tsesko (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-11117) ColUpdateTimeDeltaHistogram histogram overflow
Date Tue, 27 Sep 2016 08:54:20 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-11117?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15525530#comment-15525530
] 

Vadim Tsesko commented on CASSANDRA-11117:
------------------------------------------

I tried to trace the problem using Cassandra 3.7.
The problematic value overflowing the histogram is added in the following stack trace:
{code:java}
	at org.apache.cassandra.utils.EstimatedHistogram.add(EstimatedHistogram.java:134) [apache-cassandra-3.7.jar:3.7]
	at org.apache.cassandra.metrics.EstimatedHistogramReservoir.update(EstimatedHistogramReservoir.java:56)
[apache-cassandra-3.7.jar:3.7]
	at com.codahale.metrics.Histogram.update(Histogram.java:39) [metrics-core-3.1.0.jar:3.1.0]
	at org.apache.cassandra.metrics.TableMetrics$TableHistogram.update(TableMetrics.java:828)
[apache-cassandra-3.7.jar:3.7]
	at org.apache.cassandra.db.ColumnFamilyStore.apply(ColumnFamilyStore.java:1331) [apache-cassandra-3.7.jar:3.7]
	at org.apache.cassandra.db.Keyspace.apply(Keyspace.java:529) [apache-cassandra-3.7.jar:3.7]
	at org.apache.cassandra.db.Keyspace.apply(Keyspace.java:399) [apache-cassandra-3.7.jar:3.7]
	at org.apache.cassandra.db.Mutation.applyFuture(Mutation.java:202) [apache-cassandra-3.7.jar:3.7]
	at org.apache.cassandra.db.Mutation.apply(Mutation.java:214) [apache-cassandra-3.7.jar:3.7]
	at org.apache.cassandra.db.Mutation.apply(Mutation.java:228) [apache-cassandra-3.7.jar:3.7]
	at org.apache.cassandra.service.StorageProxy$8.runMayThrow(StorageProxy.java:1343) ~[apache-cassandra-3.7.jar:3.7]
	at org.apache.cassandra.service.StorageProxy$LocalMutationRunnable.run(StorageProxy.java:2519)
~[apache-cassandra-3.7.jar:3.7]
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) ~[na:1.8.0_102]
	at org.apache.cassandra.concurrent.AbstractLocalAwareExecutorService$FutureTask.run(AbstractLocalAwareExecutorService.java:164)
~[apache-cassandra-3.7.jar:3.7]
	at org.apache.cassandra.concurrent.AbstractLocalAwareExecutorService$LocalSessionFutureTask.run(AbstractLocalAwareExecutorService.java:136)
~[apache-cassandra-3.7.jar:3.7]
	at org.apache.cassandra.concurrent.SEPWorker.run(SEPWorker.java:105) ~[apache-cassandra-3.7.jar:3.7]
	at java.lang.Thread.run(Thread.java:745) ~[na:1.8.0_102]
{code}
The problem is caused by using time interval in {{ColumnFamilyStore.apply()}} returned by
{{Memtable.put()}} which is calculated by {{Rows.merge()}} method. It seems that in case of
an update for a nonexisting row an *absolute* time value is returned, not time delta. That
leads to very large values being sent to the histogram (as large as {{Long.MAX_VALUE / 10}}
judging by debugging on real data).
We decided to patch Cassandra and to ignore the overflowed histogram values temporarily.

> ColUpdateTimeDeltaHistogram histogram overflow
> ----------------------------------------------
>
>                 Key: CASSANDRA-11117
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-11117
>             Project: Cassandra
>          Issue Type: Bug
>            Reporter: Chris Lohfink
>            Assignee: Joel Knighton
>            Priority: Minor
>             Fix For: 2.2.x, 3.0.x, 3.x
>
>
> {code}
> getting attribute Mean of org.apache.cassandra.metrics:type=ColumnFamily,name=ColUpdateTimeDeltaHistogram
threw an exceptionjavax.management.RuntimeMBeanException: java.lang.IllegalStateException:
Unable to compute ceiling for max when histogram overflowed
> {code}
> Although the fact that this histogram has 164 buckets already, I wonder if there is something
weird with the computation thats causing this to be so large? It appears to be coming from
updates to system.local
> {code}
> org.apache.cassandra.metrics:type=Table,keyspace=system,scope=local,name=ColUpdateTimeDeltaHistogram
> {code}



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