Java线程转储:与;“等待锁定”;及;停车等候;?
在Java线程转储中,可以看到堆栈跟踪中提到的锁。Java线程转储:与;“等待锁定”;及;停车等候;?,java,multithreading,locking,jvm,thread-dump,Java,Multithreading,Locking,Jvm,Thread Dump,在Java线程转储中,可以看到堆栈跟踪中提到的锁。 似乎有三种信息: 1: -锁定(java.io.BufferedInputStream) 2: -等待锁定(org.alfresco.repo.lock.LockServiceImpl) 3: -停车等待(java.util.concurrent.SynchronousQueue$TransferStack) 1:线程已获得对象0x00002aab329f7fa0上的锁 2和3:似乎说线程正在等待所述对象上的锁变为可用… 但是2和3的区
似乎有三种信息: 1:
-锁定(java.io.BufferedInputStream)
2:
-等待锁定(org.alfresco.repo.lock.LockServiceImpl)
3:
-停车等待(java.util.concurrent.SynchronousQueue$TransferStack)
- 1:线程已获得对象0x00002aab329f7fa0上的锁
- 2和3:似乎说线程正在等待所述对象上的锁变为可用…
但是2和3的区别是什么
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
public class LockTest {
final Lock lock = new ReentrantLock(true);
synchronized void intrinsicLock() {
Thread th = new Thread(new Runnable() {
public void run() {
intrinsicLock();
}
}, "My thread");
th.start();
try {
th.join();
} catch (InterruptedException e) {
}
}
void reentrantLock() {
lock.lock();
Thread th = new Thread(new Runnable() {
public void run() {
reentrantLock();
}
}, "My thread");
th.start();
try {
th.join();
} catch (InterruptedException e) {
}
lock.unlock();
}
public static void main(String[] args) {
LockTest lockTest = new LockTest();
lockTest.intrinsicLock();
//lockTest.reentrantLock();
}
}
使用lockTest.intrinsicLock()
将获得以下线程转储:
"My thread" prio=10 tid=0x00007fffec015800 nid=0x1775 waiting for monitor entry [0x00007ffff15e5000]
java.lang.Thread.State: BLOCKED (on object monitor)
at LockTest.intrinsicLock(LockTest.java:9)
- waiting to lock <0x00000007d6a33b10> (a LockTest)
at LockTest$1.run(LockTest.java:11)
at java.lang.Thread.run(Thread.java:662)
在我看来,java.util.concurrent包几乎都使用LockSupport.park()方法来阻止线程,比如CountDownLatch、ReentrantLock,它们属于abstractqueuedsynchronized框架。
因此,问题中的第三个场景意味着您的代码最终调用了LockSupport.park()方法,因为您使用java.util.concurrent包中的concurrent类,第二个场景意味着您使用synchronized keywork和call wait()方法。我之所以这样问,是因为我正在尝试修复这个有前途的开源锁可视化工具:这两种状态之间的“区别”是什么?
- parking to wait for <0x00002aaafbf70bb8> (a java.util.concurrent.SynchronousQueue$TransferStack)
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
public class LockTest {
final Lock lock = new ReentrantLock(true);
synchronized void intrinsicLock() {
Thread th = new Thread(new Runnable() {
public void run() {
intrinsicLock();
}
}, "My thread");
th.start();
try {
th.join();
} catch (InterruptedException e) {
}
}
void reentrantLock() {
lock.lock();
Thread th = new Thread(new Runnable() {
public void run() {
reentrantLock();
}
}, "My thread");
th.start();
try {
th.join();
} catch (InterruptedException e) {
}
lock.unlock();
}
public static void main(String[] args) {
LockTest lockTest = new LockTest();
lockTest.intrinsicLock();
//lockTest.reentrantLock();
}
}
"My thread" prio=10 tid=0x00007fffec015800 nid=0x1775 waiting for monitor entry [0x00007ffff15e5000]
java.lang.Thread.State: BLOCKED (on object monitor)
at LockTest.intrinsicLock(LockTest.java:9)
- waiting to lock <0x00000007d6a33b10> (a LockTest)
at LockTest$1.run(LockTest.java:11)
at java.lang.Thread.run(Thread.java:662)
"My thread" prio=10 tid=0x00007fffec082800 nid=0x17e8 waiting on condition [0x00007ffff14eb000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000007d6a33d30> (a java.util.concurrent.locks.ReentrantLock$FairSync)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:156)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:811)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:842)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1178)
at java.util.concurrent.locks.ReentrantLock$FairSync.lock(ReentrantLock.java:201)
at java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:262)
at LockTest.reentrantLock(LockTest.java:22)
at LockTest$2.run(LockTest.java:25)
at java.lang.Thread.run(Thread.java:662)