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https://issues.apache.org/jira/browse/HBASE-28221?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17808820#comment-17808820
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Viraj Jasani commented on HBASE-28221:
--------------------------------------
{quote}While going through _MemStoreFlusher_ I realised, we do have
_flushQueueLength_
[metrics|https://github.com/apache/hbase/blob/master/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/MetricsRegionServerWrapperImpl.java#L238]
exposed already which tells us
[flushQueueSize|https://github.com/apache/hbase/blob/master/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/MemStoreFlusher.java#L504]
per RS. Isn't this the one we are looking for to figure out delayed flush
counts ?
{quote}
Good catch, i think i missed this one. Looks like this should be good for us to
alert on.
> Introduce regionserver metric for delayed flushes
> -------------------------------------------------
>
> Key: HBASE-28221
> URL: https://issues.apache.org/jira/browse/HBASE-28221
> Project: HBase
> Issue Type: Improvement
> Affects Versions: 2.4.17, 2.5.6
> Reporter: Viraj Jasani
> Assignee: Rahul Kumar
> Priority: Major
> Fix For: 2.4.18, 2.7.0, 2.5.8, 3.0.0-beta-2, 2.6.1
>
>
> If compaction is disabled temporarily to allow stabilizing hdfs load, we can
> forget re-enabling the compaction. This can result into flushes getting
> delayed for "hbase.hstore.blockingWaitTime" time (90s). While flushes do
> happen eventually after waiting for max blocking time, it is important to
> realize that any cluster cannot function well with compaction disabled for
> significant amount of time.
>
> We would also block any write requests until region is flushed (90+ sec, by
> default):
> {code:java}
> 2023-11-27 20:40:52,124 WARN [,queue=18,port=60020] regionserver.HRegion -
> Region is too busy due to exceeding memstore size limit.
> org.apache.hadoop.hbase.RegionTooBusyException: Above memstore limit,
> regionName=table1,1699923733811.4fd5e52e2133df1e347f32c646f23ab4.,
> server=server-1,60020,1699421714454, memstoreSize=1073820928,
> blockingMemStoreSize=1073741824
> at
> org.apache.hadoop.hbase.regionserver.HRegion.checkResources(HRegion.java:4200)
> at
> org.apache.hadoop.hbase.regionserver.HRegion.batchMutate(HRegion.java:3264)
> at
> org.apache.hadoop.hbase.regionserver.HRegion.batchMutate(HRegion.java:3215)
> at
> org.apache.hadoop.hbase.regionserver.RSRpcServices.doBatchOp(RSRpcServices.java:967)
> at
> org.apache.hadoop.hbase.regionserver.RSRpcServices.doNonAtomicRegionMutation(RSRpcServices.java:895)
> at
> org.apache.hadoop.hbase.regionserver.RSRpcServices.multi(RSRpcServices.java:2524)
> at
> org.apache.hadoop.hbase.protobuf.generated.ClientProtos$ClientService$2.callBlockingMethod(ClientProtos.java:36812)
> at org.apache.hadoop.hbase.ipc.RpcServer.call(RpcServer.java:2432)
> at org.apache.hadoop.hbase.ipc.CallRunner.run(CallRunner.java:124)
> at
> org.apache.hadoop.hbase.ipc.RpcExecutor$Handler.run(RpcExecutor.java:311)
> at
> org.apache.hadoop.hbase.ipc.RpcExecutor$Handler.run(RpcExecutor.java:291)
> {code}
>
> Delayed flush logs:
> {code:java}
> LOG.warn("{} has too many store files({}); delaying flush up to {} ms",
> region.getRegionInfo().getEncodedName(), getStoreFileCount(region),
> this.blockingWaitTime); {code}
> Suggestion: Introduce regionserver metric (MetricsRegionServerSource) for the
> num of flushes getting delayed due to too many store files.
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