jstack(Java Stack Trace)簡(jiǎn)介
jstack：Java進(jìn)程中線程的堆棧信息跟蹤工具。
功能簡(jiǎn)介
??jstack常用來打印Java進(jìn)程/core文件/遠(yuǎn)程調(diào)試端口的Java線程堆棧跟蹤信息恭金，包含當(dāng)前虛擬機(jī)中所有線程正在執(zhí)行的方法堆棧信息的集合操禀。
??主要用來定位線程出現(xiàn)長時(shí)間停頓的原因，如線程間死鎖横腿、死循環(huán)颓屑、請(qǐng)求外部資源導(dǎo)致的長時(shí)間等待。
命令格式
jstack [ options ] pid //Java進(jìn)程
jstack [ options ] executable core //core文件
jstack [ options ] [ server-id@ ] remote-hostname-or-IP //遠(yuǎn)程調(diào)試端口
其中options選項(xiàng)可有
| 選項(xiàng) | 作用 |
|---|---|
| -F | 當(dāng)正常輸出的請(qǐng)求不被響應(yīng)時(shí)蔑水，強(qiáng)制輸出線程堆棧 |
| -l | 除了堆棧外邢锯，顯示關(guān)于鎖的附加信息 |
| -m | 如果調(diào)用到本地方法的話，可以顯示C/C++的堆棧信息 |
其他說明
1搀别、When the specified process is running on a 64-bit Java Virtual Machine, you might need to specify the -J-d64 option, for example: jstack -J-d64 -m pid.
2丹擎、In mixed mode stack trace, the -m option does not work with the remote debug server.
3、In Windows Systems where the dbgeng.dll file is not present, Debugging Tools For Windows must be installed so these tools work.
輸出格式
jstack的輸出是該進(jìn)程下的所有線程的堆棧集合歇父，下面是一個(gè)線程的堆椀倥啵快照信息：
catalina-exec-72" daemon prio=5 tid=114 WAITING
at sun.misc.Unsafe.park(Native Method)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
Local Variable: java.util.concurrent.locks.AbstractQueuedSynchronizer$Node#294
at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:104)
at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:32)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1067)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
Local Variable: java.util.concurrent.ThreadPoolExecutor$Worker#50
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
Local Variable: org.apache.tomcat.util.threads.TaskThread$WrappingRunnable#38
at java.lang.Thread.run(Thread.java:745)
| 屬性 | 說明 |
|---|---|
| catalina-exec-72 | 線程名稱 |
| prio | 該線程JVM中的優(yōu)先級(jí) |
| os_prio | 該線程在OS中的優(yōu)先級(jí) |
| tid | JVM內(nèi)的thread id （Java-level thread ID） |
| daemon | 表明這個(gè)線程是一個(gè)守護(hù)線程 |
| nid | Native thread ID，本地操作系統(tǒng)相關(guān)的線程id |
nid說明
This ID is highly platform dependent. It's the nid in jstack thread dumps.
On Windows, it's simply the OS-level thread ID within a process.
On Linux, it's the pid of the thread (which in turn is a light-weight process).
On Solaris, it's the thread as returned by thr_self().
On Mac OS X, it is said to be the native pthread_t value.
狀?態(tài)
在jstack輸出的第二行為線程的狀態(tài)榜苫，在JVM中線程狀態(tài)使用枚舉 java.lang.Thread.State 來表示护戳，State的定義如下：
public enum State {
/**
* Thread state for a thread which has not yet started.
*/
NEW,
/**
* Thread state for a runnable thread. A thread in the runnable
* state is executing in the Java virtual machine but it may
* be waiting for other resources from the operating system
* such as processor.
*/
RUNNABLE,
/**
* Thread state for a thread blocked waiting for a monitor lock.
* A thread in the blocked state is waiting for a monitor lock
* to enter a synchronized block/method or
* reenter a synchronized block/method after calling
* {@link Object#wait() Object.wait}.
*/
BLOCKED,
/**
* Thread state for a waiting thread.
* A thread is in the waiting state due to calling one of the
* following methods:
* <ul>
* <li>{@link Object#wait() Object.wait} with no timeout</li>
* <li>{@link #join() Thread.join} with no timeout</li>
* <li>{@link LockSupport#park() LockSupport.park}</li>
* </ul>
*
* <p>A thread in the waiting state is waiting for another thread to
* perform a particular action.
*
* For example, a thread that has called <tt>Object.wait()</tt>
* on an object is waiting for another thread to call
* <tt>Object.notify()</tt> or <tt>Object.notifyAll()</tt> on
* that object. A thread that has called <tt>Thread.join()</tt>
* is waiting for a specified thread to terminate.
*/
WAITING,
/**
* Thread state for a waiting thread with a specified waiting time.
* A thread is in the timed waiting state due to calling one of
* the following methods with a specified positive waiting time:
* <ul>
* <li>{@link #sleep Thread.sleep}</li>
* <li>{@link Object#wait(long) Object.wait} with timeout</li>
* <li>{@link #join(long) Thread.join} with timeout</li>
* <li>{@link LockSupport#parkNanos LockSupport.parkNanos}</li>
* <li>{@link LockSupport#parkUntil LockSupport.parkUntil}</li>
* </ul>
*/
TIMED_WAITING,
/**
* Thread state for a terminated thread.
* The thread has completed execution.
*/
TERMINATED;
}
線程圖
Thread_life.png
| 線程狀態(tài) | 說明 |
|---|---|
| NEW | 當(dāng)線程對(duì)象創(chuàng)建時(shí)存在的狀態(tài)，此時(shí)線程不可能執(zhí)行垂睬； |
| RUNNABLE | 當(dāng)調(diào)用thread.start()后媳荒，線程變成為Runnable狀態(tài)。只要得到CPU驹饺，就可以執(zhí)行钳枕； |
| RUNNING | 線程正在執(zhí)行； |
| WAITING | 執(zhí)行thread.join()或在鎖對(duì)象調(diào)用obj.wait()等情況就會(huì)進(jìn)該狀態(tài)赏壹，表明線程正處于等待某個(gè)資源或條件發(fā)生來喚醒自己鱼炒； |
| TIMED_WAITING | 執(zhí)行Thread.sleep(long)、thread.join(long)或obj.wait(long)等就會(huì)進(jìn)該狀態(tài)蝌借，與Waiting的區(qū)別在于Timed_Waiting的等待有時(shí)間限制昔瞧； |
| BLOCKED | 如果進(jìn)入同步方法或同步代碼塊指蚁，沒有獲取到鎖，則會(huì)進(jìn)入該狀態(tài)自晰； |
| DEAD | 線程執(zhí)行完畢凝化，或者拋出了未捕獲的異常之后，會(huì)進(jìn)入dead狀態(tài)酬荞，表示該線程結(jié)束缘圈。 |
| jstack日志關(guān)鍵字 | 說 明 |
|---|---|
| deadlock | 死鎖 |
| Waiting on condition | 等待某個(gè)資源或條件發(fā)生來喚醒自己。具體需要結(jié)合jstacktrace來分析袜蚕，比如線程正在sleep糟把，網(wǎng)絡(luò)讀寫繁忙而等待 |
| Blocked | 阻塞 |
| waiting on monitor entry | 在等待獲取鎖 |
| in Object.wait() | 獲取鎖后又執(zhí)行obj.wait()放棄鎖 |
==如果說系統(tǒng)慢，那么要特別關(guān)注Blocked,Waiting on condition==
==如果說系統(tǒng)的cpu耗的高牲剃，那么肯定是線程執(zhí)行有死循環(huán)遣疯，那么此時(shí)要關(guān)注下Runable狀態(tài)。==
- 死鎖
public class DeadLock {
public static void main(String[] args) throws InterruptedException {
Object obj1 = new Object();
Object obj2 = new Object();
Object obj3 = new Object();
Thread t1 = new Thread(new SyncThread(obj1, obj2), "t1");
Thread t2 = new Thread(new SyncThread(obj2, obj3), "t2");
Thread t3 = new Thread(new SyncThread(obj3, obj1), "t3");
t1.start();
Thread.sleep(5000);
t2.start();
Thread.sleep(5000);
t3.start();
}
}
class SyncThread implements Runnable {
private Object obj1;
private Object obj2;
public SyncThread(Object o1, Object o2) {
this.obj1 = o1;
this.obj2 = o2;
}
@Override
public void run() {
String name = Thread.currentThread().getName();
System.out.println(name + " acquiring lock on " + obj1);
synchronized (obj1) {
System.out.println(name + " acquired lock on " + obj1);
work();
System.out.println(name + " acquiring lock on " + obj2);
synchronized (obj2) {
System.out.println(name + " acquired lock on " + obj2);
work();
}
System.out.println(name + " released lock on " + obj2);
}
System.out.println(name + " released lock on " + obj1);
System.out.println(name + " finished execution.");
}
private void work() {
try {
Thread.sleep(30000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
Found one Java-level deadlock:
=============================
"t3":
waiting to lock monitor 0x000000000d8fb0a8 (object 0x00000007d7cd4828, a java.lang.Object),
which is held by "t1"
"t1":
waiting to lock monitor 0x000000000560c918 (object 0x00000007d7cd4fa0, a java.lang.Object),
which is held by "t2"
"t2":
waiting to lock monitor 0x000000000560de68 (object 0x00000007d7cd4818, a java.lang.Object),
which is held by "t3"
Java stack information for the threads listed above:
===================================================
"t3":
at com.tzx.test.SyncThread.run(DeadLock.java:41)
- waiting to lock <0x00000007d7cd4828> (a java.lang.Object)
- locked <0x00000007d7cd4818> (a java.lang.Object)
at java.lang.Thread.run(Thread.java:744)
"t1":
at com.tzx.test.SyncThread.run(DeadLock.java:41)
- waiting to lock <0x00000007d7cd4fa0> (a java.lang.Object)
- locked <0x00000007d7cd4828> (a java.lang.Object)
at java.lang.Thread.run(Thread.java:744)
"t2":
at com.tzx.test.SyncThread.run(DeadLock.java:41)
- waiting to lock <0x00000007d7cd4818> (a java.lang.Object)
- locked <0x00000007d7cd4fa0> (a java.lang.Object)
at java.lang.Thread.run(Thread.java:744)
- block范例
public class Blocked {
public static void main(String[] args) {
final Thread thread = new Thread() {
@Override
public void run() {
synchronized (this) {
System.out.println(Thread.currentThread().getName());
try {
TimeUnit.SECONDS.sleep(60);
} catch (Exception e) {
}
}
}
};
thread.start();
thread.setName("thread1");
synchronized (thread) {
System.out.println(Thread.currentThread().getName());
try {
TimeUnit.SECONDS.sleep(60);
} catch (Exception e) {
}
}
}
}
2017-11-24 18:39:59
Full thread dump Java HotSpot(TM) 64-Bit Server VM (24.51-b03 mixed mode):
"RMI TCP Connection(2)-172.18.95.100" daemon prio=6 tid=0x000000000f958000 nid=0x2598 runnable [0x00000000109ce000]
java.lang.Thread.State: RUNNABLE
at java.net.SocketInputStream.socketRead0(Native Method)
at java.net.SocketInputStream.read(SocketInputStream.java:152)
at java.net.SocketInputStream.read(SocketInputStream.java:122)
at java.io.BufferedInputStream.fill(BufferedInputStream.java:235)
at java.io.BufferedInputStream.read(BufferedInputStream.java:254)
- locked <0x00000007d6695110> (a java.io.BufferedInputStream)
at java.io.FilterInputStream.read(FilterInputStream.java:83)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:538)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:811)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:670)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:744)
Locked ownable synchronizers:
- <0x00000007d62075b0> (a java.util.concurrent.ThreadPoolExecutor$Worker)
"JMX server connection timeout 14" daemon prio=6 tid=0x000000000fbe4000 nid=0x32f8 in Object.wait() [0x00000000105cf000]
java.lang.Thread.State: TIMED_WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x00000007d62dbc78> (a [I)
at com.sun.jmx.remote.internal.ServerCommunicatorAdmin$Timeout.run(ServerCommunicatorAdmin.java:168)
- locked <0x00000007d62dbc78> (a [I)
at java.lang.Thread.run(Thread.java:744)
Locked ownable synchronizers:
- None
"RMI Scheduler(0)" daemon prio=6 tid=0x000000000fbe3000 nid=0xcc0 waiting on condition [0x00000000104cf000]
java.lang.Thread.State: TIMED_WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000007d61806c0> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:226)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(AbstractQueuedSynchronizer.java:2082)
at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1090)
at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:807)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1068)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:744)
Locked ownable synchronizers:
- None
"RMI TCP Connection(1)-172.18.95.100" daemon prio=6 tid=0x000000000fbe9000 nid=0x3b9c runnable [0x00000000103ce000]
java.lang.Thread.State: RUNNABLE
at java.net.SocketInputStream.socketRead0(Native Method)
at java.net.SocketInputStream.read(SocketInputStream.java:152)
at java.net.SocketInputStream.read(SocketInputStream.java:122)
at java.io.BufferedInputStream.fill(BufferedInputStream.java:235)
at java.io.BufferedInputStream.read(BufferedInputStream.java:254)
- locked <0x00000007d62a64d0> (a java.io.BufferedInputStream)
at java.io.FilterInputStream.read(FilterInputStream.java:83)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:538)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:811)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:670)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:744)
Locked ownable synchronizers:
- <0x00000007d6203998> (a java.util.concurrent.ThreadPoolExecutor$Worker)
"RMI TCP Accept-0" daemon prio=6 tid=0x000000000fbe6000 nid=0x38c0 runnable [0x00000000101be000]
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:398)
at java.net.PlainSocketImpl.accept(PlainSocketImpl.java:198)
- locked <0x00000007d6181e30> (a java.net.SocksSocketImpl)
at java.net.ServerSocket.implAccept(ServerSocket.java:530)
at java.net.ServerSocket.accept(ServerSocket.java:498)
at sun.management.jmxremote.LocalRMIServerSocketFactory$1.accept(LocalRMIServerSocketFactory.java:52)
at sun.rmi.transport.tcp.TCPTransport$AcceptLoop.executeAcceptLoop(TCPTransport.java:388)
at sun.rmi.transport.tcp.TCPTransport$AcceptLoop.run(TCPTransport.java:360)
at java.lang.Thread.run(Thread.java:744)
Locked ownable synchronizers:
- None
"thread1" prio=6 tid=0x000000000f339000 nid=0x2728 waiting for monitor entry [0x000000000f89f000]
java.lang.Thread.State: BLOCKED (on object monitor)
at com.tzx.test.Blocked$1.run(Blocked.java:12)
- waiting to lock <0x00000007d5d2a758> (a com.tzx.test.Blocked$1)
Locked ownable synchronizers:
- None
"Service Thread" daemon prio=6 tid=0x000000000da67000 nid=0x2de4 runnable [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
Locked ownable synchronizers:
- None
"C2 CompilerThread1" daemon prio=10 tid=0x000000000da63800 nid=0x2ccc waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
Locked ownable synchronizers:
- None
"C2 CompilerThread0" daemon prio=10 tid=0x000000000da54800 nid=0x1aec waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
Locked ownable synchronizers:
- None
"Attach Listener" daemon prio=10 tid=0x000000000da54000 nid=0x39fc waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
Locked ownable synchronizers:
- None
"Signal Dispatcher" daemon prio=10 tid=0x00000000056de800 nid=0x3bac runnable [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
Locked ownable synchronizers:
- None
"Finalizer" daemon prio=8 tid=0x00000000056ce000 nid=0x778 in Object.wait() [0x000000000ed9f000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x00000007d5c05568> (a java.lang.ref.ReferenceQueue$Lock)
at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:135)
- locked <0x00000007d5c05568> (a java.lang.ref.ReferenceQueue$Lock)
at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:151)
at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:189)
Locked ownable synchronizers:
- None
"Reference Handler" daemon prio=10 tid=0x000000000da14000 nid=0x1254 in Object.wait() [0x000000000ec9f000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x00000007d5c050f0> (a java.lang.ref.Reference$Lock)
at java.lang.Object.wait(Object.java:503)
at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:133)
- locked <0x00000007d5c050f0> (a java.lang.ref.Reference$Lock)
Locked ownable synchronizers:
- None
"main" prio=6 tid=0x00000000055e6000 nid=0x2da8 waiting on condition [0x000000000558f000]
java.lang.Thread.State: TIMED_WAITING (sleeping)
at java.lang.Thread.sleep(Native Method)
at java.lang.Thread.sleep(Thread.java:340)
at java.util.concurrent.TimeUnit.sleep(TimeUnit.java:360)
at com.tzx.test.Blocked.main(Blocked.java:27)
- locked <0x00000007d5d2a758> (a com.tzx.test.Blocked$1)
Locked ownable synchronizers:
- None
"VM Thread" prio=10 tid=0x000000000da12000 nid=0x3434 runnable
"GC task thread#0 (ParallelGC)" prio=6 tid=0x00000000055fc000 nid=0x2da4 runnable
"GC task thread#1 (ParallelGC)" prio=6 tid=0x00000000055fe000 nid=0x10fc runnable
"GC task thread#2 (ParallelGC)" prio=6 tid=0x00000000055ff800 nid=0x32b0 runnable
"GC task thread#3 (ParallelGC)" prio=6 tid=0x0000000005602800 nid=0x534 runnable
"VM Periodic Task Thread" prio=10 tid=0x000000000f2b0800 nid=0x2f78 waiting on condition
