如何使用JDK自带工具定位 JVM 问题
使用 JDK 自带工具查看 JVM 情况
//启动10个线程IntStream.rangeClosed(1, 10).mapToObj(i -> new Thread(() -> {while (true) {//每一个线程都是一个死循环，休眠10秒，打印10M数据String payload = IntStream.rangeClosed(1, 10000000).mapToObj(__ -> "a").collect(Collectors.joining("")) + UUID.randomUUID().toString();try {TimeUnit.SECONDS.sleep(10);} catch (InterruptedException e) {e.printStackTrace();}System.out.println(payload.length());}})).forEach(Thread::start);TimeUnit.HOURS.sleep(1);
<plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId><configuration><mainClass>org.geekbang.time.commonmistakes.troubleshootingtools.jdktool.CommonMistakesApplication</mainClass></configuration></plugin>
java -jar common-mistakes-0.0.1-SNAPSHOT.jar -Xms1g -Xmx1gjps
~ jps1270722261 Launcher23864 common-mistakes-0.0.1-SNAPSHOT.jar15608 RemoteMavenServer3623243 Main23868 Jps22893 KotlinCompileDaemon
jinfo
~ jinfo 23864Java System Properties:#Wed Jan 29 12:49:47 CST 2020...=zhuye=\:=10.15.2=Java(TM) SE Runtime Environment=UTF-8=Java HotSpot(TM) 64-Bit Server VM...VM Flags::CICompilerCount=4 -XX:ConcGCThreads=2 -XX:G1ConcRefinementThreads=8 -XX:G1HeapRegionSize=1048576 -XX:GCDrainStackTargetSize=64 -XX:InitialHeapSize=268435456 -XX:MarkStackSize=4194304 -XX:MaxHeapSize=4294967296 -XX:MaxNewSize=2576351232 -XX:MinHeapDeltaBytes=1048576 -XX:NonNMethodCodeHeapSize=5835340 -XX:NonProfiledCodeHeapSize=122911450 -XX:ProfiledCodeHeapSize=122911450 -XX:ReservedCodeCacheSize=251658240 -XX:+SegmentedCodeCache -XX:+UseCompressedClassPointers -XX:+UseCompressedOops -XX:+UseG1GCVM Arguments:java_command: common-mistakes-0.0.1-SNAPSHOT.jar -Xms1g -Xmx1gjava_class_path (initial): common-mistakes-0.0.1-SNAPSHOT.jarLauncher Type: SUN_STANDARD
System.out.println("VM options");System.out.println(ManagementFactory.getRuntimeMXBean().getInputArguments().stream().collect(Collectors.joining(System.lineSeparator())));System.out.println("Program arguments");System.out.println(Arrays.stream(args).collect(Collectors.joining(System.lineSeparator())));
➜ target git:(master) ✗ java -Xms1g -Xmx1g -jar common-mistakes-0.0.1-SNAPSHOT.jar testVM options-Xms1g-Xmx1gProgram argumentstest
jvisualvm
jstat
➜ ~ jstat -gcutil 23940 5000 100S0 S1 E O M CCS YGC YGCT FGC FGCT CGC CGCT GCT0.00 100.00 0.36 87.63 94.30 81.06 539 14.021 33 3.972 837 0.976 18.9680.00 100.00 0.60 69.51 94.30 81.06 540 14.029 33 3.972 839 0.978 18.9790.00 0.00 0.50 99.81 94.27 81.03 548 14.143 34 4.002 840 0.981 19.1260.00 100.00 0.59 70.47 94.27 81.03 549 14.177 34 4.002 844 0.985 19.1640.00 100.00 0.57 99.85 94.32 81.09 550 14.204 34 4.002 845 0.990 19.1960.00 100.00 0.65 77.69 94.32 81.09 559 14.469 36 4.198 847 0.993 19.6590.00 100.00 0.65 77.69 94.32 81.09 559 14.469 36 4.198 847 0.993 19.6590.00 100.00 0.70 35.54 94.32 81.09 567 14.763 37 4.378 853 1.001 20.1420.00 100.00 0.70 41.22 94.32 81.09 567 14.763 37 4.378 853 1.001 20.1420.00 100.00 1.89 96.76 94.32 81.09 574 14.943 38 4.487 859 1.007 20.4380.00 100.00 1.39 39.20 94.32 81.09 575 14.946 38 4.487 861 1.010 20.442
其中，S0 表示 Survivor0 区占用百分比，S1 表示 Survivor1 区占用百分比，E 表示 Eden 区占用百分比，O 表示老年代占用百分比，M 表示元数据区占用百分比，YGC 表示年轻代回收次数，YGCT 表示年轻代回收耗时，FGC 表示老年代回收次数，FGCT 表示老年代回收耗时。
jstack
➜ ~ jstack 239402020-01-29 13:08:15Full thread dump Java HotSpot(TM) 64-Bit Server VM (11.0.3+12-LTS mixed mode):..."main" #1 prio=5 os_prio=31 cpu=440.66ms elapsed=574.86s tid=0x00007ffdd9800000 nid=0x2803 waiting on condition [0x0000700003849000]java.lang.Thread.State: TIMED_WAITING (sleeping)at java.lang.Thread.sleep(java.base@11.0.3/Native Method)at java.lang.Thread.sleep(java.base@11.0.3/Thread.java:339)at java.util.concurrent.TimeUnit.sleep(java.base@11.0.3/TimeUnit.java:446)at org.geekbang.time.commonmistakes.troubleshootingtools.jdktool.CommonMistakesApplication.main(CommonMistakesApplication.java:41)at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(java.base@11.0.3/Native Method)at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(java.base@11.0.3/NativeMethodAccessorImpl.java:62)at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(java.base@11.0.3/DelegatingMethodAccessorImpl.java:43)at java.lang.reflect.Method.invoke(java.base@11.0.3/Method.java:566)at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:48)at org.springframework.boot.loader.Launcher.launch(Launcher.java:87)at org.springframework.boot.loader.Launcher.launch(Launcher.java:51)at org.springframework.boot.loader.JarLauncher.main(JarLauncher.java:52)"Thread-1"java.lang.Thread.State: TIMED_WAITING (sleeping)at java.lang.Thread.sleep(java.base@11.0.3/Native Method)at java.lang.Thread.sleep(java.base@11.0.3/Thread.java:339)at java.util.concurrent.TimeUnit.sleep(java.base@11.0.3/TimeUnit.java:446)at org.geekbang.time.commonmistakes.troubleshootingtools.jdktool.CommonMistakesApplication.lambda$null$1(CommonMistakesApplication.java:33)at org.geekbang.time.commonmistakes.troubleshootingtools.jdktool.CommonMistakesApplication$$Lambda$41/0x00000008000a8c40.run(Unknown Source)at java.lang.Thread.run(java.base@11.0.3/Thread.java:834)...
jcmd
-Xms1g -Xmx1g -XX:ThreadStackSize=256k -XX:NativeMemoryTracking=detail➜ ~ jcmd 24404 VM.native_memory summary24404:Native Memory Tracking:Total: reserved=6635310KB, committed=5337110KB- Java Heap (reserved=1048576KB, committed=1048576KB)(mmap: reserved=1048576KB, committed=1048576KB)- Class (reserved=1066233KB, committed=15097KB)(classes #902)(malloc=9465KB #908)(mmap: reserved=1056768KB, committed=5632KB)- Thread (reserved=4209797KB, committed=4209797KB)(thread #32)(stack: reserved=4209664KB, committed=4209664KB)(malloc=96KB #165)(arena=37KB #59)- Code (reserved=249823KB, committed=2759KB)(malloc=223KB #730)(mmap: reserved=249600KB, committed=2536KB)- GC (reserved=48700KB, committed=48700KB)(malloc=10384KB #135)(mmap: reserved=38316KB, committed=38316KB)- Compiler (reserved=186KB, committed=186KB)(malloc=56KB #105)(arena=131KB #7)- Internal (reserved=9693KB, committed=9693KB)(malloc=9661KB #2585)(mmap: reserved=32KB, committed=32KB)- Symbol (reserved=2021KB, committed=2021KB)(malloc=1182KB #334)(arena=839KB #1)- Native Memory Tracking (reserved=85KB, committed=85KB)(malloc=5KB #53)(tracking overhead=80KB)- Arena Chunk (reserved=196KB, committed=196KB)(malloc=196KB)
jcmd 24781 help官方文档：https://docs.oracle.com/javase/8/docs/technotes/tools/
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