JDK命令行工具的監控

JVM參數類型

標準參數

  • -help
  • -server -client
  • -version -showversion
  • -cp -classpath

X參數

  • -Xint 解釋執行
  • -Xcomp 第一次執行使用就編譯成本地代碼 (interpret)
  • -Xmixed 混合模式,JVM自己決定是否編譯成本地代碼(compile)
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XX參數

Boolean類型

  • 格式:-XX:[+-] <name> 表示啓動或者禁用name屬性
  • 例如:
    • -XX:+UserConcMarkSweepGC 啓用CMS垃圾收集器
    • -XX:+UseG1GC 啓用G1垃圾收集器

非Boolean類型

  • 格式:-XX:<name>=<value> 表示name屬性的值是vlaue
  • 例如:
    • -XX:MaxGCPauseMillis=500 表示GC最大停頓時間500ms
    • -XX:GCTimeRatio=19

-Xmx -Xms 不是X參數,而是XX參數
-Xms 等價於 -XX:InitialHeapSize
-Xmx 等價於 -XX:MaxHeapSize

jinfo查看JVM運行參數

  • -XX:+PrintFlagsInitial
  • -XX:+PrintFlagsFinal
  • -XX:UnlockExperimentalVMOptions 解鎖實驗參數
  • -XX:+UnlockDiagnosticVMOptions 解鎖診斷參數
  • -XX:+PrintCommandLineFlags 打印命令行參數

【命令格式】
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  • 查看最大內存:jinfo -flag MaxHeapSize <pid>
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  • 查看垃圾回收器:jinfo -flag <GC> <pid>
    • jinfo -flag UseConcMarkSweepGC 2444
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    • jinfo -flag UseG1GC 2444在這裏插入圖片描述
    • jinfo -flag UseParallelGC 2444在這裏插入圖片描述

jstat查看JVM統計信息

【命令格式】
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  • -class :jstat -class 2444 1000 10
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    查看已加載類和卸載類的個數和大小,以及加載和卸載花費的時間

  • -gc:jstat -gc 2444 1000 3
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    S0U、S1C、S0U、S1U:S0和S1的總量和使用量(Capacity,Utilization)
    EC、EU:Eden區總量和使用量
    OC、OU:Old區總量和使用量
    MC、MU:Metaspace區總量和使用量
    CCSC、CCSU:壓縮類空間總量和使用量
    YGC、YGCT:YoungGC次數與時間
    FGC、FGCT:FullGC次數與時間
    GCT:總GC時間

  • -compile:jstat -compiler 2444
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jmap 分析內存溢出

演示內存溢出

@RestController
public class MemoryController {

    private List<User> userList = new ArrayList<>();
    private List<Class<?>> classList = new ArrayList<>();

    //-Xmx32M -Xms32M
    // heap溢出
    @GetMapping("/heap")
    public String heap(){
        int i = 0;

        while (true){
            userList.add(new User(i++, UUID.randomUUID().toString()));
        }
    }

    //-XX:MetaspaceSize=32M -XX:MetaspaceSize=32M
    // metaspace溢出
    @GetMapping("/nonheap")
    public String nonHeap(){
        int i = 0;
        while (true){
        	// 使用ASM工具生成字節碼文件	
            classList.addAll(MetaSpace.createClasses());
        }
    }
}

heap溢出:
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metaspace溢出:
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導出內存映像文件

  • 內存溢出自動導出

    • -XX:+HeapDumpOnOutOfMemoryError
    • -XX:HeapDumpPath=./
  • jmap手動導出
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    • jmap -dump:format=b,file=heap.bin 15988
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    • jmap -heap 15988
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jstack查看線程狀態

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jstack 1388
C:\Users\where\Desktop>jstack 1388
2019-08-11 22:22:44
Full thread dump Java HotSpot(TM) 64-Bit Server VM (25.152-b16 mixed mode):

"DestroyJavaVM" #41 prio=5 os_prio=0 tid=0x000000001876c800 nid=0x238c waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"http-nio-8080-Acceptor" #39 daemon prio=5 os_prio=0 tid=0x000000001876a000 nid=0xb6c runnable [0x000000001a98f000]
   java.lang.Thread.State: RUNNABLE
        at sun.nio.ch.ServerSocketChannelImpl.accept0(Native Method)
        at sun.nio.ch.ServerSocketChannelImpl.accept(ServerSocketChannelImpl.java:422)
        at sun.nio.ch.ServerSocketChannelImpl.accept(ServerSocketChannelImpl.java:250)
        - locked <0x00000000ff76a6e8> (a java.lang.Object)
        at org.apache.tomcat.util.net.NioEndpoint.serverSocketAccept(NioEndpoint.java:463)
        at org.apache.tomcat.util.net.NioEndpoint.serverSocketAccept(NioEndpoint.java:73)
        at org.apache.tomcat.util.net.Acceptor.run(Acceptor.java:95)
        at java.lang.Thread.run(Thread.java:748)

"http-nio-8080-ClientPoller" #38 daemon prio=5 os_prio=0 tid=0x0000000018771000 nid=0x31d8 runnable [0x000000001a88e000]
   java.lang.Thread.State: RUNNABLE
        at sun.nio.ch.WindowsSelectorImpl$SubSelector.poll0(Native Method)
        at sun.nio.ch.WindowsSelectorImpl$SubSelector.poll(WindowsSelectorImpl.java:296)
        at sun.nio.ch.WindowsSelectorImpl$SubSelector.access$400(WindowsSelectorImpl.java:278)
        at sun.nio.ch.WindowsSelectorImpl.doSelect(WindowsSelectorImpl.java:159)
        at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:86)
        - locked <0x00000000ff8454f0> (a sun.nio.ch.Util$3)
        - locked <0x00000000ff8454e0> (a java.util.Collections$UnmodifiableSet)
        - locked <0x00000000ff845390> (a sun.nio.ch.WindowsSelectorImpl)
        at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:97)
        at org.apache.tomcat.util.net.NioEndpoint$Poller.run(NioEndpoint.java:708)
        at java.lang.Thread.run(Thread.java:748)

"http-nio-8080-exec-1" #28 daemon prio=5 os_prio=0 tid=0x000000001875f800 nid=0x1980 waiting on condition [0x0000000019e8e000]
   java.lang.Thread.State: WAITING (parking)
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for  <0x00000000ff81af68> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
        at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
        at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
        at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:107)
        at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:33)
        at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
        at java.lang.Thread.run(Thread.java:748)

"http-nio-8080-BlockPoller" #27 daemon prio=5 os_prio=0 tid=0x000000001875e000 nid=0x3c5c runnable [0x0000000019d8e000]
   java.lang.Thread.State: RUNNABLE
        at sun.nio.ch.WindowsSelectorImpl$SubSelector.poll0(Native Method)
        at sun.nio.ch.WindowsSelectorImpl$SubSelector.poll(WindowsSelectorImpl.java:296)
        at sun.nio.ch.WindowsSelectorImpl$SubSelector.access$400(WindowsSelectorImpl.java:278)
        at sun.nio.ch.WindowsSelectorImpl.doSelect(WindowsSelectorImpl.java:159)
        at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:86)
        - locked <0x00000000ff775c70> (a sun.nio.ch.Util$3)
        - locked <0x00000000ff7753d8> (a java.util.Collections$UnmodifiableSet)
        - locked <0x00000000ff775220> (a sun.nio.ch.WindowsSelectorImpl)
        at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:97)
        at org.apache.tomcat.util.net.NioBlockingSelector$BlockPoller.run(NioBlockingSelector.java:313)

"container-0" #26 prio=5 os_prio=0 tid=0x00000000186a1800 nid=0x14c4 waiting on condition [0x0000000019a8f000]
   java.lang.Thread.State: TIMED_WAITING (sleeping)
        at java.lang.Thread.sleep(Native Method)
        at org.apache.catalina.core.StandardServer.await(StandardServer.java:570)
        at org.springframework.boot.web.embedded.tomcat.TomcatWebServer$1.run(TomcatWebServer.java:179)

"Catalina-utility-1" #24 prio=1 os_prio=-2 tid=0x00000000186be000 nid=0x3dcc waiting on condition [0x000000001988e000]
   java.lang.Thread.State: TIMED_WAITING (parking)
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for  <0x00000000fee26350> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
        at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:215)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(AbstractQueuedSynchronizer.java:2078)
        at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1093)
        at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:809)
        at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
        at java.lang.Thread.run(Thread.java:748)

"RMI Scheduler(0)" #18 daemon prio=5 os_prio=0 tid=0x0000000016701800 nid=0x1d6c waiting on condition [0x00000000177bf000]
   java.lang.Thread.State: TIMED_WAITING (parking)
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for  <0x00000000fe051338> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
        at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:215)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(AbstractQueuedSynchronizer.java:2078)
        at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1093)
        at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:809)
        at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)

"RMI TCP Accept-61297" #14 daemon prio=5 os_prio=0 tid=0x000000001649e800 nid=0x2f6c runnable [0x0000000016d0e000]
   java.lang.Thread.State: RUNNABLE
        at java.net.DualStackPlainSocketImpl.accept0(Native Method)
        at java.net.DualStackPlainSocketImpl.socketAccept(DualStackPlainSocketImpl.java:131)
        at java.net.AbstractPlainSocketImpl.accept(AbstractPlainSocketImpl.java:409)
        at java.net.PlainSocketImpl.accept(PlainSocketImpl.java:199)
        - locked <0x00000000fe641650> (a java.net.SocksSocketImpl)
        at java.net.ServerSocket.implAccept(ServerSocket.java:545)
        at java.net.ServerSocket.accept(ServerSocket.java:513)
        at sun.rmi.transport.tcp.TCPTransport$AcceptLoop.executeAcceptLoop(TCPTransport.java:400)
        at sun.rmi.transport.tcp.TCPTransport$AcceptLoop.run(TCPTransport.java:372)
        at java.lang.Thread.run(Thread.java:748)

"RMI TCP Accept-0" #13 daemon prio=5 os_prio=0 tid=0x0000000016486000 nid=0x208c runnable [0x0000000016c0f000]
   java.lang.Thread.State: RUNNABLE
        at java.net.DualStackPlainSocketImpl.accept0(Native Method)
        at java.net.DualStackPlainSocketImpl.socketAccept(DualStackPlainSocketImpl.java:131)
        at java.net.AbstractPlainSocketImpl.accept(AbstractPlainSocketImpl.java:409)
        at java.net.PlainSocketImpl.accept(PlainSocketImpl.java:199)
        - locked <0x00000000fe641af8> (a java.net.SocksSocketImpl)
        at java.net.ServerSocket.implAccept(ServerSocket.java:545)
        at java.net.ServerSocket.accept(ServerSocket.java:513)
        at sun.rmi.transport.tcp.TCPTransport$AcceptLoop.executeAcceptLoop(TCPTransport.java:400)
        at sun.rmi.transport.tcp.TCPTransport$AcceptLoop.run(TCPTransport.java:372)
        at java.lang.Thread.run(Thread.java:748)

"Service Thread" #11 daemon prio=9 os_prio=0 tid=0x0000000015966800 nid=0xf58 runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"C1 CompilerThread3" #10 daemon prio=9 os_prio=2 tid=0x00000000158c7800 nid=0x33d0 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"C2 CompilerThread2" #9 daemon prio=9 os_prio=2 tid=0x00000000158c5000 nid=0xcc8 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"C2 CompilerThread1" #8 daemon prio=9 os_prio=2 tid=0x00000000158c4000 nid=0x305c waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"C2 CompilerThread0" #7 daemon prio=9 os_prio=2 tid=0x00000000158a6000 nid=0x2194 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Monitor Ctrl-Break" #6 daemon prio=5 os_prio=0 tid=0x00000000158b7000 nid=0x53c runnable [0x0000000015e0f000]
   java.lang.Thread.State: RUNNABLE
        at java.net.SocketInputStream.socketRead0(Native Method)
        at java.net.SocketInputStream.socketRead(SocketInputStream.java:116)
        at java.net.SocketInputStream.read(SocketInputStream.java:171)
        at java.net.SocketInputStream.read(SocketInputStream.java:141)
        at sun.nio.cs.StreamDecoder.readBytes(StreamDecoder.java:284)
        at sun.nio.cs.StreamDecoder.implRead(StreamDecoder.java:326)
        at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:178)
        - locked <0x00000000fe399b50> (a java.io.InputStreamReader)
        at java.io.InputStreamReader.read(InputStreamReader.java:184)
        at java.io.BufferedReader.fill(BufferedReader.java:161)
        at java.io.BufferedReader.readLine(BufferedReader.java:324)
        - locked <0x00000000fe399b50> (a java.io.InputStreamReader)
        at java.io.BufferedReader.readLine(BufferedReader.java:389)
        at com.intellij.rt.execution.application.AppMainV2$1.run(AppMainV2.java:64)

"Attach Listener" #5 daemon prio=5 os_prio=2 tid=0x00000000156a2800 nid=0x940 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Signal Dispatcher" #4 daemon prio=9 os_prio=2 tid=0x000000001564d000 nid=0x3be4 runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Finalizer" #3 daemon prio=8 os_prio=1 tid=0x0000000013743800 nid=0x9e8 in Object.wait() [0x0000000015b0e000]
   java.lang.Thread.State: WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - waiting on <0x00000000fe63aef0> (a java.lang.ref.ReferenceQueue$Lock)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:143)
        - locked <0x00000000fe63aef0> (a java.lang.ref.ReferenceQueue$Lock)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:164)
        at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:209)

"Reference Handler" #2 daemon prio=10 os_prio=2 tid=0x0000000003089800 nid=0x3d38 in Object.wait() [0x000000001560e000]
   java.lang.Thread.State: WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - waiting on <0x00000000fe399bf8> (a java.lang.ref.Reference$Lock)
        at java.lang.Object.wait(Object.java:502)
        at java.lang.ref.Reference.tryHandlePending(Reference.java:191)
        - locked <0x00000000fe399bf8> (a java.lang.ref.Reference$Lock)
        at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:153)

"VM Thread" os_prio=2 tid=0x0000000013738000 nid=0xf8 runnable

"GC task thread#0 (ParallelGC)" os_prio=0 tid=0x0000000002fab000 nid=0x1614 runnable

"GC task thread#1 (ParallelGC)" os_prio=0 tid=0x0000000002fad000 nid=0x29e8 runnable

"GC task thread#2 (ParallelGC)" os_prio=0 tid=0x0000000002fae800 nid=0x3a74 runnable

"GC task thread#3 (ParallelGC)" os_prio=0 tid=0x0000000002fb0000 nid=0x910 runnable

"GC task thread#4 (ParallelGC)" os_prio=0 tid=0x0000000002fb2000 nid=0x3fe8 runnable

"GC task thread#5 (ParallelGC)" os_prio=0 tid=0x0000000002fb4800 nid=0x134c runnable

"GC task thread#6 (ParallelGC)" os_prio=0 tid=0x0000000002fb7800 nid=0x3890 runnable

"GC task thread#7 (ParallelGC)" os_prio=0 tid=0x0000000002fb8800 nid=0x3a8 runnable

"VM Periodic Task Thread" os_prio=2 tid=0x00000000164ae000 nid=0x748 waiting on condition

JNI global references: 1034
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