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Posted on通过Java/JMX得到full GC次数? - 高级语言虚拟机
群组首页 → 编程语言 → 高级语言虚拟机 → 知识库 → JVM实战 → 通过Java/JMX得到full GC次数? 原创作者: RednaxelaFX 阅读:2261次 评论:1条 更新时间:2011-05-26
今天有个同事问如何能通过JMX获取到某个Java进程的full GC次数: 引用
hi,问个问题,怎们在java中获取到full gc的次数呢? 我现在用jmx的那个得到了gc次数,不过不能细化出来full gc的次数 Java代码
- for (final GarbageCollectorMXBean garbageCollector
- : ManagementFactory.getGarbageCollectorMXBeans()) {
- gcCounts += garbageCollector.getCollectionCount();
}
for (final GarbageCollectorMXBean garbageCollector : ManagementFactory.getGarbageCollectorMXBeans()) { gcCounts += garbageCollector.getCollectionCount(); } 你比如我现在是这样拿次数的 我回答说因为full GC概念只有在分代式GC的上下文中才存在,而JVM并不强制要求GC使用分代式实现,所以JMX提供的标准MXBean API里不提供“full GC次数”这样的方法也正常。 既然“full GC”本来就是非常平台相关的概念,那就hack一点,用平台相关的代码来解决问题好了。这些GC的MXBean都是有名字的,而主流的JVM的GC名字相对稳定,非要通过JMX得到full GC次数的话,用名字来判断一下就好了。 举个例子来看看。通过JDK 6自带的JConsole工具来查看相关的MXBean的话,可以看到, GC的MXBean在这个位置: 这个例子是用server模式启动JConsole的,使用的是ParallelScavenge GC,它的年老代对应的收集器在这里: 该收集器的总收集次数在此,这也就是full GC的次数: 于是只要知道我们用的JVM提供的GC MXBean的名字与分代的关系,就可以知道full GC的次数了。 Java代码写起来冗长,这帖就不用Java来写例子了,反正API是一样的,意思能表达清楚就OK。 用一个Groovy脚本简单演示一下适用于Oracle (Sun) HotSpot与Oracle (BEA) JRockit的GC统计程序: Groovy代码import java.lang.management.ManagementFactory
- printGCStats = {
- def youngGenCollectorNames = [
- // Oracle (Sun) HotSpot
- // -XX:+UseSerialGC
- 'Copy',
- // -XX:+UseParNewGC
- 'ParNew',
- // -XX:+UseParallelGC
- 'PS Scavenge',
- // Oracle (BEA) JRockit
- // -XgcPrio:pausetime
- 'Garbage collection optimized for short pausetimes Young Collector',
- // -XgcPrio:throughput
- 'Garbage collection optimized for throughput Young Collector',
- // -XgcPrio:deterministic
- 'Garbage collection optimized for deterministic pausetimes Young Collector'
- ]
- def oldGenCollectorNames = [
- // Oracle (Sun) HotSpot
- // -XX:+UseSerialGC
- 'MarkSweepCompact',
- // -XX:+UseParallelGC and (-XX:+UseParallelOldGC or -XX:+UseParallelOldGCCompacting)
- 'PS MarkSweep',
- // -XX:+UseConcMarkSweepGC
- 'ConcurrentMarkSweep',
- // Oracle (BEA) JRockit
- // -XgcPrio:pausetime
- 'Garbage collection optimized for short pausetimes Old Collector',
- // -XgcPrio:throughput
- 'Garbage collection optimized for throughput Old Collector',
- // -XgcPrio:deterministic
- 'Garbage collection optimized for deterministic pausetimes Old Collector'
- ]
- R: {
- ManagementFactory.garbageCollectorMXBeans.each {
- def name = it.name
- def count = it.collectionCount
- def gcType;
- switch (name) {
- case youngGenCollectorNames:
- gcType = 'Minor Collection'
- break
- case oldGenCollectorNames:
- gcType = 'Major Collection'
- break
- default:
- gcType = 'Unknown Collection Type'
- break
- }
- println "$count <- $gcType: $name"
- }
- }
- }
printGCStats()
import java.lang.management.ManagementFactory printGCStats = { def youngGenCollectorNames = [ // Oracle (Sun) HotSpot // -XX:+UseSerialGC 'Copy', // -XX:+UseParNewGC 'ParNew', // -XX:+UseParallelGC 'PS Scavenge', // Oracle (BEA) JRockit // -XgcPrio:pausetime 'Garbage collection optimized for short pausetimes Young Collector', // -XgcPrio:throughput 'Garbage collection optimized for throughput Young Collector', // -XgcPrio:deterministic 'Garbage collection optimized for deterministic pausetimes Young Collector' ] def oldGenCollectorNames = [ // Oracle (Sun) HotSpot // -XX:+UseSerialGC 'MarkSweepCompact', // -XX:+UseParallelGC and (-XX:+UseParallelOldGC or -XX:+UseParallelOldGCCompacting) 'PS MarkSweep', // -XX:+UseConcMarkSweepGC 'ConcurrentMarkSweep', // Oracle (BEA) JRockit // -XgcPrio:pausetime 'Garbage collection optimized for short pausetimes Old Collector', // -XgcPrio:throughput 'Garbage collection optimized for throughput Old Collector', // -XgcPrio:deterministic 'Garbage collection optimized for deterministic pausetimes Old Collector' ] R: { ManagementFactory.garbageCollectorMXBeans.each { def name = it.name def count = it.collectionCount def gcType; switch (name) { case youngGenCollectorNames: gcType = 'Minor Collection' break case oldGenCollectorNames: gcType = 'Major Collection' break default: gcType = 'Unknown Collection Type' break } println "$count <- $gcType: $name" } } } printGCStats() 执行可以看到类似这样的输出: Command prompt代码5 <- Minor Collection: Copy
0 <- Major Collection: MarkSweepCompact
5 <- Minor Collection: Copy 0 <- Major Collection: MarkSweepCompact ↑这是用client模式的HotSpot执行得到的; Command prompt代码0 <- Minor Collection: Garbage collection optimized for throughput Young Collector
0 <- Major Collection: Garbage collection optimized for throughput Old Collector
0 <- Minor Collection: Garbage collection optimized for throughput Young Collector 0 <- Major Collection: Garbage collection optimized for throughput Old Collector ↑这是用JRockit R28在32位Windows上的默认模式得到的。 通过上述方法,要包装起来方便以后使用的话也很简单,例如下面Groovy程序: Groovy代码import java.lang.management.ManagementFactory
- class GCStats {
- static final List
YoungGenCollectorNames = [ - // Oracle (Sun) HotSpot
- // -XX:+UseSerialGC
- 'Copy',
- // -XX:+UseParNewGC
- 'ParNew',
- // -XX:+UseParallelGC
- 'PS Scavenge',
- // Oracle (BEA) JRockit
- // -XgcPrio:pausetime
- 'Garbage collection optimized for short pausetimes Young Collector',
- // -XgcPrio:throughput
- 'Garbage collection optimized for throughput Young Collector',
- // -XgcPrio:deterministic
- 'Garbage collection optimized for deterministic pausetimes Young Collector'
- ]
- static final List
OldGenCollectorNames = [ - // Oracle (Sun) HotSpot
- // -XX:+UseSerialGC
- 'MarkSweepCompact',
- // -XX:+UseParallelGC and (-XX:+UseParallelOldGC or -XX:+UseParallelOldGCCompacting)
- 'PS MarkSweep',
- // -XX:+UseConcMarkSweepGC
- 'ConcurrentMarkSweep',
- // Oracle (BEA) JRockit
- // -XgcPrio:pausetime
- 'Garbage collection optimized for short pausetimes Old Collector',
- // -XgcPrio:throughput
- 'Garbage collection optimized for throughput Old Collector',
- // -XgcPrio:deterministic
- 'Garbage collection optimized for deterministic pausetimes Old Collector'
- ]
- static int getYoungGCCount() {
- ManagementFactory.garbageCollectorMXBeans.inject(0) { youngGCCount, gc ->
- if (YoungGenCollectorNames.contains(gc.name))
- youngGCCount + gc.collectionCount
- else
- youngGCCount
- }
- }
- static int getFullGCCount() {
- ManagementFactory.garbageCollectorMXBeans.inject(0) { fullGCCount, gc ->
- if (OldGenCollectorNames.contains(gc.name))
- fullGCCount + gc.collectionCount
- else
- fullGCCount
- }
- }
}
import java.lang.management.ManagementFactory class GCStats { static final ListYoungGenCollectorNames = [ // Oracle (Sun) HotSpot // -XX:+UseSerialGC 'Copy', // -XX:+UseParNewGC 'ParNew', // -XX:+UseParallelGC 'PS Scavenge', // Oracle (BEA) JRockit // -XgcPrio:pausetime 'Garbage collection optimized for short pausetimes Young Collector', // -XgcPrio:throughput 'Garbage collection optimized for throughput Young Collector', // -XgcPrio:deterministic 'Garbage collection optimized for deterministic pausetimes Young Collector' ] static final List OldGenCollectorNames = [ // Oracle (Sun) HotSpot // -XX:+UseSerialGC 'MarkSweepCompact', // -XX:+UseParallelGC and (-XX:+UseParallelOldGC or -XX:+UseParallelOldGCCompacting) 'PS MarkSweep', // -XX:+UseConcMarkSweepGC 'ConcurrentMarkSweep', // Oracle (BEA) JRockit // -XgcPrio:pausetime 'Garbage collection optimized for short pausetimes Old Collector', // -XgcPrio:throughput 'Garbage collection optimized for throughput Old Collector', // -XgcPrio:deterministic 'Garbage collection optimized for deterministic pausetimes Old Collector' ] static int getYoungGCCount() { ManagementFactory.garbageCollectorMXBeans.inject(0) { youngGCCount, gc -> if (YoungGenCollectorNames.contains(gc.name)) youngGCCount + gc.collectionCount else youngGCCount } } static int getFullGCCount() { ManagementFactory.garbageCollectorMXBeans.inject(0) { fullGCCount, gc -> if (OldGenCollectorNames.contains(gc.name)) fullGCCount + gc.collectionCount else fullGCCount } } } 用的时候: Groovysh代码 D:>\sdk\groovy-1.7.2\bin\groovysh
- Groovy Shell (1.7.2, JVM: 1.6.0_20)
- Type 'help' or '\h' for help.
- groovy:000> GCStats.fullGCCount
- ===> 0
- groovy:000> System.gc()
- ===> null
- groovy:000> GCStats.fullGCCount
- ===> 1
- groovy:000> System.gc()
- ===> null
- groovy:000> System.gc()
- ===> null
- groovy:000> GCStats.fullGCCount
- ===> 3
- groovy:000> GCStats.youngGCCount
- ===> 9
- groovy:000> GCStats.youngGCCount
- ===> 9
- groovy:000> GCStats.youngGCCount
- ===> 9
- groovy:000> System.gc()
- ===> null
- groovy:000> GCStats.youngGCCount
- ===> 9
- groovy:000> GCStats.fullGCCount
- ===> 4
- groovy:000> quit
D:>\sdk\groovy-1.7.2\bin\groovysh Groovy Shell (1.7.2, JVM: 1.6.0_20) Type 'help' or '\h' for help. -------------------------------------------------- groovy:000> GCStats.fullGCCount ===> 0 groovy:000> System.gc() ===> null groovy:000> GCStats.fullGCCount ===> 1 groovy:000> System.gc() ===> null groovy:000> System.gc() ===> null groovy:000> GCStats.fullGCCount ===> 3 groovy:000> GCStats.youngGCCount ===> 9 groovy:000> GCStats.youngGCCount ===> 9 groovy:000> GCStats.youngGCCount ===> 9 groovy:000> System.gc() ===> null groovy:000> GCStats.youngGCCount ===> 9 groovy:000> GCStats.fullGCCount ===> 4 groovy:000> quit 这是在Sun JDK 6 update 20上跑的。顺带一提,如果这是跑在JRockit上的话,那full GC的次数就不会增加——因为JRockit里System.gc()默认是触发young GC的;请不要因为Sun HotSpot的默认行为而认为System.gc()总是会触发full GC的。 关于JMX的MXBean的使用,也可以参考下面两篇文档: Groovy and JMX Monitoring the JVM Heap with JRuby 如何更快的启动eclipse
评论 共 1 条 请登录后发表评论
1 楼 xgj1988 2011-04-27 15:07
SUN jdk 使用FULL GC 是如下的几种之一? Java代码
- static final List
OldGenCollectorNames = [ - // Oracle (Sun) HotSpot
- // -XX:+UseSerialGC
- 'MarkSweepCompact',
- // -XX:+UseParallelGC and (-XX:+UseParallelOldGC or -XX:+UseParallelOldGCCompacting)
- 'PS MarkSweep',
- // -XX:+UseConcMarkSweepGC
- 'ConcurrentMarkSweep',
]
static final ListOldGenCollectorNames = [ // Oracle (Sun) HotSpot // -XX:+UseSerialGC 'MarkSweepCompact', // -XX:+UseParallelGC and (-XX:+UseParallelOldGC or -XX:+UseParallelOldGCCompacting) 'PS MarkSweep', // -XX:+UseConcMarkSweepGC 'ConcurrentMarkSweep', ] 这几个是young gc? Java代码 'Copy',
- // -XX:+UseParNewGC
- 'ParNew',
- // -XX:+UseParallelGC
- 'PS Scavenge',
- 'Copy', // -XX:+UseParNewGC 'ParNew', // -XX:+UseParallelGC 'PS Scavenge',
根据名字判断来获取full gc
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文章信息
- 由fantasy在2010-12-16创建
由fantasy在2011-05-26更新
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