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Posted to commits@cassandra.apache.org by "Jeff Griffith (JIRA)" <ji...@apache.org> on 2016/05/11 13:59:12 UTC
[jira] [Commented] (CASSANDRA-11117) ColUpdateTimeDeltaHistogram
histogram overflow
[ https://issues.apache.org/jira/browse/CASSANDRA-11117?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15280152#comment-15280152 ]
Jeff Griffith commented on CASSANDRA-11117:
-------------------------------------------
the code that updates this is here:
{code}
public void apply(DecoratedKey key, ColumnFamily columnFamily, SecondaryIndexManager.Updater indexer, OpOrder.Group opGroup, ReplayPosition replayPosition)
{
long start = System.nanoTime();
Memtable mt = data.getMemtableFor(opGroup, replayPosition);
final long timeDelta = mt.put(key, columnFamily, indexer, opGroup);
maybeUpdateRowCache(key);
metric.samplers.get(Sampler.WRITES).addSample(key.getKey(), key.hashCode(), 1);
metric.writeLatency.addNano(System.nanoTime() - start);
if(timeDelta < Long.MAX_VALUE)
metric.colUpdateTimeDeltaHistogram.update(timeDelta);
}
{code}
That "if (timeDelta < Long.MAX_VALUE)" looks ill-conceived since there are no longs > max long, but i don't really know what exactly is overflowing in the histogram.
> 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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