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https://issues.apache.org/jira/browse/GEODE-8520?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17200949#comment-17200949
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ASF GitHub Bot commented on GEODE-8520:
---------------------------------------
kirklund commented on a change in pull request #5536:
URL: https://github.com/apache/geode/pull/5536#discussion_r493739655
##########
File path:
geode-core/src/main/java/org/apache/geode/management/internal/beans/stats/GCStatsMonitor.java
##########
@@ -39,69 +39,71 @@
* @see org.apache.geode.management.internal.beans.stats.MBeanStatsMonitor
*/
public class GCStatsMonitor extends MBeanStatsMonitor {
+ // this class uses these volatile variables to make sure reads are reading
the latest values
+ // it is not using the parent's siteMap which is not volatile to keep the
stats values.
private volatile long collections = 0;
private volatile long collectionTime = 0;
- long getCollections() {
- return collections;
- }
-
- long getCollectionTime() {
- return collectionTime;
- }
-
public GCStatsMonitor(String name) {
super(name);
}
- void decreasePrevValues(Map<String, Number> statsMap) {
- collections -= statsMap.getOrDefault(StatsKey.VM_GC_STATS_COLLECTIONS,
0).longValue();
- collectionTime -=
statsMap.getOrDefault(StatsKey.VM_GC_STATS_COLLECTION_TIME, 0).longValue();
- }
-
- void increaseStats(String name, Number value) {
- if (name.equals(StatsKey.VM_GC_STATS_COLLECTIONS)) {
- collections += value.longValue();
- return;
- }
-
- if (name.equals(StatsKey.VM_GC_STATS_COLLECTION_TIME)) {
- collectionTime += value.longValue();
- return;
+ @Override
+ // this will be called multiple times with different collector's stats
+ public void addStatisticsToMonitor(Statistics stats) {
+ monitor.addListener(this);// if already listener is added this will be a
no-op
+ monitor.addStatistics(stats);
+
+ // stats map should keep the sum of all the GC stats
+ StatisticDescriptor[] descriptors = stats.getType().getStatistics();
+ for (StatisticDescriptor d : descriptors) {
+ String name = d.getName();
+ Number value = stats.get(d);
+ if (name.equals(StatsKey.VM_GC_STATS_COLLECTIONS)) {
+ collections += value.longValue();
Review comment:
Using += on a volatile field is not thread safe. I recommend changing
collections and collectionTime to be AtomicLong instances. Then you can use
incrementAndGet() instead of +=. Even if multiple threads do not currently
invoke this method, maybe they will in the future.
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> GarbageCollectionCount metric is showing negative values
> --------------------------------------------------------
>
> Key: GEODE-8520
> URL: https://issues.apache.org/jira/browse/GEODE-8520
> Project: Geode
> Issue Type: Bug
> Components: management
> Affects Versions: 1.13.0
> Reporter: Jinmei Liao
> Priority: Major
> Labels: GeodeOperationAPI, pull-request-available
>
> sometimes the memberMBean's garbageCollectionCount and garbageCollectionTime
> metriics are showing negative values.
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