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https://issues.apache.org/jira/browse/HBASE-11617?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14079867#comment-14079867
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Lars Hofhansl commented on HBASE-11617:
---------------------------------------
The problem is that getStats(), is called periodically to dump the replication
metrics to the logs and it calls refreshAgeOfLastAppliedOp() (because there is
not other way to get the metric's value).
Your solution will work and is maybe the easiest to do. (you do not need to
turn age into a member, though)
> AgeOfLastAppliedOp in MetricsSink got increased when no new replication sink
> OP
> --------------------------------------------------------------------------------
>
> Key: HBASE-11617
> URL: https://issues.apache.org/jira/browse/HBASE-11617
> Project: HBase
> Issue Type: Bug
> Components: Replication
> Affects Versions: 0.98.2
> Reporter: Demai Ni
> Assignee: Demai Ni
> Priority: Minor
> Fix For: 0.99.0, 0.98.5, 2.0.0
>
>
> AgeOfLastAppliedOp in MetricsSink.java is to indicate the time an edit sat in
> the 'replication queue' before it got replicated(aka applied)
> {code}
> /**
> * Set the age of the last applied operation
> *
> * @param timestamp The timestamp of the last operation applied.
> * @return the age that was set
> */
> public long setAgeOfLastAppliedOp(long timestamp) {
> lastTimestampForAge = timestamp;
> long age = System.currentTimeMillis() - lastTimestampForAge;
> rms.setGauge(SINK_AGE_OF_LAST_APPLIED_OP, age);
> return age;
> }
> {code}
> In the following scenario:
> 1) at 7:00am a sink op is applied, and the SINK_AGE_OF_LAST_APPLIED_OP is
> set for example 100ms;
> 2) and then NO new Sink op occur.
> 3) when a refreshAgeOfLastAppliedOp() is invoked at 8:00am. Instead of
> return the 100ms, the AgeOfLastAppliedOp become 1hour + 100ms,
> It was because that refreshAgeOfLastAppliedOp() get invoked periodically by
> getStats().
> proposed fix:
> {code}
> ---
> hbase-server/src/main/java/org/apache/hadoop/hbase/replication/regionserver/MetricsSink.java
> +++
> hbase-server/src/main/java/org/apache/hadoop/hbase/replication/regionserver/MetricsSink.java
> @@ -35,6 +35,7 @@ public class MetricsSink {
>
> private MetricsReplicationSource rms;
> private long lastTimestampForAge = System.currentTimeMillis();
> + private long age = 0;
>
> public MetricsSink() {
> rms =
> CompatibilitySingletonFactory.getInstance(MetricsReplicationSource.class);
> @@ -47,8 +48,12 @@ public class MetricsSink {
> * @return the age that was set
> */
> public long setAgeOfLastAppliedOp(long timestamp) {
> - lastTimestampForAge = timestamp;
> - long age = System.currentTimeMillis() - lastTimestampForAge;
> + if (lastTimestampForAge != timestamp) {
> + lastTimestampForAge = timestamp;
> + this.age = System.currentTimeMillis() - lastTimestampForAge;
> + } else {
> + this.age = 0;
> + }
> rms.setGauge(SINK_AGE_OF_LAST_APPLIED_OP, age);
> return age;
> }
> {code}
> detail discussion in [dev@hbase |
> http://mail-archives.apache.org/mod_mbox/hbase-dev/201407.mbox/%3CCAOEq2C5BKMXAM2Fv4LGVb_Ktek-Pm%3DhjOi33gSHX-2qHqAou6w%40mail.gmail.com%3E
> ]
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