util/util-jvm: Add gc pause stats for all collectors

Problem

Currently we only have gc pause stats for the ParNew collector, but
we'd like to be able to see this information for the G1 pools.

Solution

Add collection duration stats for all collector pools. Keep the jvm/gc/eden/pause_msec
stat for compatibility, but this will be the same as jvm/gc/ParNew/pause_msec.

Differential Revision: https://phabricator.twitter.biz/D1176049

CHANGELOG.rst

@@ -7,6 +7,12 @@ Note that ``PHAB_ID=#`` and ``RB_ID=#`` correspond to associated messages in com
 Unreleased
 ----------
 
+New Features
+~~~~~~~~~~~~
+
+* util-jvm: Add gc pause stats for all collector pools, including G1. ``PHAB_ID=D1176049``
+
+
 24.5.0
 ------
 

util-jvm/src/main/scala/com/twitter/jvm/JvmStats.scala

@@ -1,5 +1,6 @@
 package com.twitter.jvm
 
+import com.sun.management.GarbageCollectionNotificationInfo
 import com.twitter.conversions.StringOps._
 import com.twitter.finagle.stats.MetricBuilder.GaugeType
 import com.twitter.finagle.stats.Bytes
@@ -9,6 +10,10 @@ import com.twitter.finagle.stats.exp.Expression
 import com.twitter.finagle.stats.exp.ExpressionSchema
 import java.lang.management.BufferPoolMXBean
 import java.lang.management.ManagementFactory
+import javax.management.Notification
+import javax.management.NotificationEmitter
+import javax.management.NotificationListener
+import javax.management.openmbean.CompositeData
 import scala.collection.mutable
 import scala.jdk.CollectionConverters._
 
@@ -186,6 +191,26 @@ object JvmStats {
         gc.getCollectionTime.toFloat
       }
 
+      val gcPauseStat = gcStats.stat(name, "pause_msec")
+      gc.asInstanceOf[NotificationEmitter].addNotificationListener(
+          new NotificationListener {
+            override def handleNotification(
+              notification: Notification,
+              handback: Any
+            ): Unit = {
+              notification.getType
+              if (notification.getType == GarbageCollectionNotificationInfo.GARBAGE_COLLECTION_NOTIFICATION) {
+                gcPauseStat.add(
+                  GarbageCollectionNotificationInfo
+                    .from(notification.getUserData
+                      .asInstanceOf[CompositeData]).getGcInfo.getDuration)
+              }
+            }
+          },
+          null,
+          null
+        )
+
       gcStats.registerExpression(
         ExpressionSchema(s"gc_cycles", Expression(poolCycles.metadata))
           .withLabel(ExpressionSchema.Role, "jvm")