zentol commented on a change in pull request #13640:
URL: https://github.com/apache/flink/pull/13640#discussion_r505409970
##########
File path:
flink-runtime/src/main/java/org/apache/flink/runtime/metrics/util/MetricUtils.java
##########
@@ -214,6 +219,29 @@ static void instantiateNonHeapMemoryMetrics(final
MetricGroup metricGroup) {
instantiateMemoryUsageMetrics(metricGroup, () ->
ManagementFactory.getMemoryMXBean().getNonHeapMemoryUsage());
}
+ @VisibleForTesting
+ static void instantiateMetaspaceMemoryMetrics(final MetricGroup
parentMetricGroup) {
+ final List<MemoryPoolMXBean> memoryPoolMXBeans =
ManagementFactory.getMemoryPoolMXBeans()
+ .stream()
+ .filter(bean -> "Metaspace".equals(bean.getName()))
+ .collect(Collectors.toList());
+
+ if (memoryPoolMXBeans.isEmpty()) {
+ LOG.warn("No memory pool named 'Metaspace' is present.
The '{}' metric group is not going to be instantiated.",
METRIC_GROUP_METASPACE_NAME);
Review comment:
```suggestion
LOG.info("Metaspace metrics will not be exposed because
no pool named 'Metaspace' could be found. This could be due to the used JVM.");
```
Users typically don't like warning they can't do anything about, and the
message is relatively cryptic ("what is a metric group? what is the consequence
of it not being instantiated?"
##########
File path:
flink-runtime/src/main/java/org/apache/flink/runtime/metrics/util/MetricUtils.java
##########
@@ -214,6 +219,29 @@ static void instantiateNonHeapMemoryMetrics(final
MetricGroup metricGroup) {
instantiateMemoryUsageMetrics(metricGroup, () ->
ManagementFactory.getMemoryMXBean().getNonHeapMemoryUsage());
}
+ @VisibleForTesting
+ static void instantiateMetaspaceMemoryMetrics(final MetricGroup
parentMetricGroup) {
+ final List<MemoryPoolMXBean> memoryPoolMXBeans =
ManagementFactory.getMemoryPoolMXBeans()
+ .stream()
+ .filter(bean -> "Metaspace".equals(bean.getName()))
+ .collect(Collectors.toList());
+
+ if (memoryPoolMXBeans.isEmpty()) {
+ LOG.warn("No memory pool named 'Metaspace' is present.
The '{}' metric group is not going to be instantiated.",
METRIC_GROUP_METASPACE_NAME);
+ return;
+ }
+
+ final MetricGroup metricGroup =
parentMetricGroup.addGroup(METRIC_GROUP_METASPACE_NAME);
+ final Iterator<MemoryPoolMXBean> beanIterator =
memoryPoolMXBeans.iterator();
+
+ final MemoryPoolMXBean firstPool = beanIterator.next();
+ instantiateMemoryUsageMetrics(metricGroup, firstPool::getUsage);
+
+ if (beanIterator.hasNext()) {
+ LOG.warn("More than one memory pool named '{}' are
present. Only the first pool was used for instantiating the metric.",
METRIC_GROUP_METASPACE_NAME);
Review comment:
I'm fairly sure that this is mostly a theoretical issue; for it to be
usable via JMX the MBeans require some unique identification, and according to
the MemoryPoolMXBean javadocs the only unique part of the identifier is in fact
the name. In other words, multiple pools of this name being present would
likely be a bug in the JVM.
We can keep this check, but it should be on debug imo.
It is also a bit odd to use the metric group name as the pool name, when we
used another string for the actual filtering (as in, move "Metaspace" into a
constant, use that here, and maybe make METRIC_GROUP_METASPACE_NAME an alias
for this constant.)
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