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https://issues.apache.org/jira/browse/GEODE-8520?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17201095#comment-17201095
]
ASF GitHub Bot commented on GEODE-8520:
---------------------------------------
jinmeiliao commented on a change in pull request #5536:
URL: https://github.com/apache/geode/pull/5536#discussion_r493896136
##########
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();
+ } else if (name.equals(StatsKey.VM_GC_STATS_COLLECTION_TIME)) {
+ collectionTime += value.longValue();
+ }
}
}
@Override
public Number getStatistic(String statName) {
if (statName.equals(StatsKey.VM_GC_STATS_COLLECTIONS)) {
- return getCollections();
+ return collections;
}
if (statName.equals(StatsKey.VM_GC_STATS_COLLECTION_TIME)) {
- return getCollectionTime();
+ return collectionTime;
}
-
return 0;
}
@Override
public void handleNotification(StatisticsNotification notification) {
- decreasePrevValues(statsMap);
-
+ // sum up all the count and all the time in the stats included in this
notification
+ long totalCount = 0;
+ long totalTime = 0;
for (StatisticId statId : notification) {
StatisticDescriptor descriptor = statId.getStatisticDescriptor();
String name = descriptor.getName();
Number value;
-
try {
value = notification.getValue(statId);
} catch (StatisticNotFoundException e) {
value = 0;
}
-
log(name, value);
- increaseStats(name, value);
- statsMap.put(name, value);
+ if (name.equals(StatsKey.VM_GC_STATS_COLLECTIONS)) {
+ totalCount += value.longValue();
+ }
+
+ else if (name.equals(StatsKey.VM_GC_STATS_COLLECTION_TIME)) {
+ totalTime += value.longValue();
+ }
}
+
+ collections = totalCount;
+ collectionTime = totalTime;
}
Review comment:
> > then what would those count/time mean though. It's not right to
report just a single one of them. It's not right to sum them up either then....
>
> The stats notification stuff is specifically designed to report only
changes. As a result, old gen and new gen CGs are almost always reported
independently (unless they both happen to change during a single sample).
>
> I think that's why the old code was doing the weird stuff. It was trying
to track the previous value for each kind of GC, so that when a new value
arrived, it could add in just the change in that kind of GC. Decrementing and
incrementing was a puzzling way to do that, but that was the goal.
>
> Here's a way that seems simpler to me than decrementing/incrementing. I'll
use collections as an example, but it's the same for collectionTime.
>
> * Create a map that records the latest value for each GC type.
> * Create a field that records the sum of values for all types. This is
what gets reported via getCollections()
> * When a new kind of GC is added via addStatisticsToMonitor()…
>
> 1. Store the initial value for that GC type in the map.
> 2. Sum the values of all GC types in the map, and store the sum in the
field.
> * When a notification arrives…
>
> 1. Store the new value for that GC type in the map.
> 2. Sum the values of all GC types in the map, and store the sum in the
field.
Yes, this sounds like a better idea. I will implement it.
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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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