Jackie-Jiang commented on code in PR #19872:
URL: https://github.com/apache/pinot/pull/19872#discussion_r4277925226
##########
pinot-spi/src/main/java/org/apache/pinot/spi/utils/CommonConstants.java:
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@@ -49,9 +49,7 @@ private CommonConstants() {
public static final String CONFIG_OF_BROKER_EVENT_LISTENER_CLASS_NAME =
"factory.className";
public static final String CONFIG_OF_REQUEST_CONTEXT_TRACKED_HEADER_KEYS =
"request.context.tracked.header.keys";
public static final String DEFAULT_METRICS_FACTORY_CLASS_NAME =
- //"org.apache.pinot.plugin.metrics.compound.CompoundPinotMetricsFactory";
- "org.apache.pinot.plugin.metrics.yammer.YammerMetricsFactory";
- //"org.apache.pinot.plugin.metrics.dropwizard.DropwizardMetricsFactory";
+ "org.apache.pinot.plugin.metrics.dropwizard.DropwizardMetricsFactory";
Review Comment:
[P1] Bound timer reservoirs before switching the default
The default switch activates `DropwizardMetricsRegistry.newTimer()`, which
uses `SlidingTimeWindowArrayReservoir(15, TimeUnit.MINUTES)` and retains every
observation for 15 minutes, whereas Yammer caps its reservoir at 1,028 samples.
At 10,000 updates/sec, one timer retains nine million timestamp/value pairs—at
least 144 MB before overhead. Each successful broker query updates table,
global, and workload timers
(`BaseSingleStageBrokerRequestHandler.java:1076–1081`), plus phase timers. JMX
reads also repeatedly copy and sort these populations for individual statistics
and percentiles. This materially increases heap usage and scrape costs for
existing deployments.
Please use a bounded reservoir, such as Dropwizard's exponentially decaying
reservoir, before enabling this backend by default.
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