stoty commented on code in PR #1431:
URL: https://github.com/apache/phoenix/pull/1431#discussion_r863505525
##########
phoenix-core/src/main/java/org/apache/phoenix/monitoring/MetricUtil.java:
##########
@@ -38,4 +46,22 @@ public static MetricsStopWatch getMetricsStopWatch(boolean
isRequestMetricsEnabl
return new MetricsStopWatch(true);
}
+ // We need to cover the case when JmxCacheBuster has just stopped the
HBase metrics
+ // system, and not accidentally overwrite the DefaultMetricsSystem
singleton.
+ // See PHOENIX-6699
+ public static boolean isDefaultMetricsInitialized() {
+ try {
+ MetricsSystemImpl metrics = (MetricsSystemImpl)
DefaultMetricsSystem.instance();
+ Field prefixField =
MetricsSystemImpl.class.getDeclaredField("prefix");
Review Comment:
> Could we somehow separate the Phoenix client-side-only metrics from the
execution pathway of the Phoenix server-side metrics? I imagine this is no
easier to do.
We're veering into territories that are beyond my knowledge of the metrics
system.
AFAICT the Hadoop metrics system always uses the DefaultMetrics object, I
haven't seen anything that points to using multiple MetricsSystem objects at
the same time.
This is mostly fine, as we can add/remove metrics from this default
MetricsSystem objects, and this doesn't cause any problems, and this means that
we add the additional Phoenix metrics in the RS dynamically, and they can be
accessed in a unified way.
Pre HBase 1.4, Phoenix didn't use the metrics2 framework for its client
metrics, and it had to be accessed programmatically (no JMX). I don't think we
want that.
The only problem comes from the fact that SOMETHING has to initialize a
DefaultMetrics object on the Phoenix client side once before the Metrics System
can be used, and
1. HBase (server side) and Phoenix (anywhere) attempt this
2. While DefaultMetrics is protected from re-initialization, the stop/start
sequence preformed by JmxCacheBuster defeats this, hence this bug.
I have also tried to simply disable the DefaultMetrics initialization from
Phoenix, but in that case the Metrics System wasn't initialized at all on the
client side.
All in all, I think that my current solution is good enough, and I'm not
convinced that expliring alternatives is worth the time (even though I asked
for them from you)
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