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  • 第一种synchronized方式死锁:线程thread1先获取锁locka,然后在同步块里嵌套竞争锁lockb。而线程thread2先获取锁lockb,然后在同步块里嵌套竞争锁locka(此时已经被线程thread1拥有,而thread1在等待lockb,而lockb...

    第一种synchronized方式死锁:

    线程thread1先获取锁locka,然后在同步块里嵌套竞争锁lockb。

    而线程thread2先获取锁lockb,然后在同步块里嵌套竞争锁locka

    (此时已经被线程thread1拥有,而thread1在等待lockb,而lockb被thread2拥有,thread2在等待locka……无线循环)。

    package com.app.test;

    import org.apache.poi.util.SystemOutLogger;

    /**

    * Created by lirong5 on 2016/5/24.

    */

    public class SyncDeadLock{

    private static Object locka = new Object();

    private static Object lockb = new Object();

    public static void main(String[] args){

    new SyncDeadLock().deadLock();

    }

    private void deadLock(){

    Thread thread1 = new Thread(new Runnable() {

    @Override

    public void run() {

    synchronized (locka){

    try{

    Thread.sleep(500);

    System.out.println("locka ing!");

    }catch(Exception e){

    e.printStackTrace();

    }

    synchronized (lockb){

    System.out.println("lockb ing!");

    }

    }

    }

    },"thread1");

    Thread thread2 = new Thread(new Runnable() {

    @Override

    public void run() {

    synchronized (lockb){

    try{

    Thread.sleep(500);

    System.out.println("lockb ing!");

    }catch(Exception e){

    e.printStackTrace();

    }

    synchronized (locka){

    System.out.println("locka ing!");

    }

    }

    }

    },"thread2");

    thread1.start();

    thread2.start();

    }

    }

    第二种concurrent包Lock错误使用,导致死锁:

    lock.unlock();释放锁使用地方不规范,导致死锁不能正常释放!

    package com.app.test;

    import java.util.concurrent.locks.Lock;

    import java.util.concurrent.locks.ReentrantLock;

    /**

    * Created by lirong5 on 2016/5/24.

    */

    public class LockDeadDemo {

    public static void main(String[] args){

    final DeadLockBean deadLockBean = new DeadLockBean();

    Thread threadA = new Thread(new Runnable() {

    @Override

    public void run() {

    try {

    Thread.sleep(300);

    } catch (InterruptedException e) {

    e.printStackTrace();

    }

    try {

    deadLockBean.productDeadLock();

    } catch (Throwable throwable) {

    throwable.printStackTrace();

    }

    }

    },"threadA");

    Thread threadB = new Thread(new Runnable() {

    @Override

    public void run() {

    try {

    Thread.sleep(310);

    } catch (InterruptedException e) {

    e.printStackTrace();

    }

    try {

    deadLockBean.productDeadLock();

    } catch (Throwable throwable) {

    throwable.printStackTrace();

    }

    }

    },"threadB");

    threadA.start();

    threadB.start();

    try {

    System.out.println("main线程即将被join");

    threadA.join();

    threadB.join();

    System.out.println("main线程从join中恢复");

    } catch (InterruptedException e) {

    e.printStackTrace();

    }

    }

    public static class DeadLockBean{

    private Lock lock = new ReentrantLock();

    public void productDeadLock() throws Throwable {

    System.out.println(Thread.currentThread().getName() + " 进入了方法!");

    lock.lock();

    try{

    System.out.println(Thread.currentThread().getName() + " 已经执行了!");

    throw new Throwable("人为抛出异常Throwable");//关键代码行1,

    //throw new Exception("人为抛出异常Exception");//关键代码行2,不会死锁,会在catch(Exception e中被捕获),嵌套lock.unlock()并释放

    }catch(Exception e){

    System.out.println(Thread.currentThread().getName()+" 发生异常catch!");

    //lock.unlock();//关键代码行3,不建议在这里释放,假如发生【关键代码行1】会产生死锁

    }finally{

    System.out.println(Thread.currentThread().getName()+" 发生异常finally!");

    lock.unlock();//关键代码行4,无论发生何种异常,均会释放锁。

    }

    //lock.unlock();//关键代码行5,假如发生不能捕获异常,将跳出方法体,不执行此处

    System.out.println(Thread.currentThread().getName() + " tryCatch外释放锁!");

    }

    }

    }

    展开全文
  • 一个简单的死锁例子

    2021-03-28 12:27:38
    import java.util.concurrent.locks.Lock; import java.util.concurrent.locks.ReentrantLock; /** * @author Dongguabai * @description * @date 2021-03-28 ... 可以看到发生了死锁。两个线程在互相等待对方释放锁。

    代码如下:

    package com.example.demo.service;
    
    import java.util.concurrent.locks.Lock;
    import java.util.concurrent.locks.ReentrantLock;
    
    /**
     * @author Dongguabai
     * @description
     * @date 2021-03-28 12:18
     */
    public class Test2 {
    
        static Lock lock1 = new ReentrantLock();
        static Lock lock2 = new ReentrantLock();
    
        public static void main(String[] args) {
            new Thread(()->{
                lock1.lock();
                System.out.println(Thread.currentThread()+"】】已经获取lock1准备获取lock2");
                lock2.lock();
                lock1.unlock();
                lock2.unlock();
            }).start();
    
    
            new Thread(()->{
                lock2.lock();
                System.out.println(Thread.currentThread()+"】】已经获取lock2准备获取lock1");
                lock1.lock();
                lock1.unlock();
                lock2.unlock();
            }).start();
        }
    }
    

    通过 jstack 很容易可以看出来:

    ➜  ~ jps           
    560 NutstoreGUI
    4642 Jps
    4531 Launcher
    4532 Test2
    4264 
    4330 RemoteMavenServer
    ➜  ~ jstack -l 4532 > 1.txt
    
    2021-03-28 12:24:40
    Full thread dump Java HotSpot(TM) 64-Bit Server VM (25.201-b09 mixed mode):
    
    "Attach Listener" #14 daemon prio=9 os_prio=31 tid=0x00007f87a485b000 nid=0x5803 waiting on condition [0x0000000000000000]
       java.lang.Thread.State: RUNNABLE
    
       Locked ownable synchronizers:
    	- None
    
    "DestroyJavaVM" #13 prio=5 os_prio=31 tid=0x00007f879e80e800 nid=0x1003 waiting on condition [0x0000000000000000]
       java.lang.Thread.State: RUNNABLE
    
       Locked ownable synchronizers:
    	- None
    
    "Thread-1" #12 prio=5 os_prio=31 tid=0x00007f87a2119000 nid=0x5703 waiting on condition [0x000070000f26c000]
       java.lang.Thread.State: WAITING (parking)
    	at sun.misc.Unsafe.park(Native Method)
    	- parking to wait for  <0x00000007957e1a60> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)
    	at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
    	at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:836)
    	at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:870)
    	at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1199)
    	at java.util.concurrent.locks.ReentrantLock$NonfairSync.lock(ReentrantLock.java:209)
    	at java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:285)
    	at com.example.demo.service.Test2.lambda$main$1(Test2.java:29)
    	at com.example.demo.service.Test2$$Lambda$2/193064360.run(Unknown Source)
    	at java.lang.Thread.run(Thread.java:748)
    
       Locked ownable synchronizers:
    	- <0x00000007957e1a90> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)
    
    "Thread-0" #11 prio=5 os_prio=31 tid=0x00007f87a2118000 nid=0xa803 waiting on condition [0x000070000f169000]
       java.lang.Thread.State: WAITING (parking)
    	at sun.misc.Unsafe.park(Native Method)
    	- parking to wait for  <0x00000007957e1a90> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)
    	at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
    	at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:836)
    	at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:870)
    	at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1199)
    	at java.util.concurrent.locks.ReentrantLock$NonfairSync.lock(ReentrantLock.java:209)
    	at java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:285)
    	at com.example.demo.service.Test2.lambda$main$0(Test2.java:20)
    	at com.example.demo.service.Test2$$Lambda$1/94438417.run(Unknown Source)
    	at java.lang.Thread.run(Thread.java:748)
    
       Locked ownable synchronizers:
    	- <0x00000007957e1a60> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)
    
    "Service Thread" #10 daemon prio=9 os_prio=31 tid=0x00007f87a485a800 nid=0x4103 runnable [0x0000000000000000]
       java.lang.Thread.State: RUNNABLE
    
       Locked ownable synchronizers:
    	- None
    
    "C1 CompilerThread3" #9 daemon prio=9 os_prio=31 tid=0x00007f879f882800 nid=0x4303 waiting on condition [0x0000000000000000]
       java.lang.Thread.State: RUNNABLE
    
       Locked ownable synchronizers:
    	- None
    
    "C2 CompilerThread2" #8 daemon prio=9 os_prio=31 tid=0x00007f879f882000 nid=0x3e03 waiting on condition [0x0000000000000000]
       java.lang.Thread.State: RUNNABLE
    
       Locked ownable synchronizers:
    	- None
    
    "C2 CompilerThread1" #7 daemon prio=9 os_prio=31 tid=0x00007f879f880800 nid=0x3d03 waiting on condition [0x0000000000000000]
       java.lang.Thread.State: RUNNABLE
    
       Locked ownable synchronizers:
    	- None
    
    "C2 CompilerThread0" #6 daemon prio=9 os_prio=31 tid=0x00007f879f87f800 nid=0x3c03 waiting on condition [0x0000000000000000]
       java.lang.Thread.State: RUNNABLE
    
       Locked ownable synchronizers:
    	- None
    
    "Monitor Ctrl-Break" #5 daemon prio=5 os_prio=31 tid=0x00007f879f87e000 nid=0x4703 runnable [0x000070000ea54000]
       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 <0x0000000795858900> (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 <0x0000000795858900> (a java.io.InputStreamReader)
    	at java.io.BufferedReader.readLine(BufferedReader.java:389)
    	at com.intellij.rt.execution.application.AppMainV2$1.run(AppMainV2.java:64)
    
       Locked ownable synchronizers:
    	- None
    
    "Signal Dispatcher" #4 daemon prio=9 os_prio=31 tid=0x00007f879e808800 nid=0x3a03 runnable [0x0000000000000000]
       java.lang.Thread.State: RUNNABLE
    
       Locked ownable synchronizers:
    	- None
    
    "Finalizer" #3 daemon prio=8 os_prio=31 tid=0x00007f87a1823800 nid=0x4f03 in Object.wait() [0x000070000e748000]
       java.lang.Thread.State: WAITING (on object monitor)
    	at java.lang.Object.wait(Native Method)
    	- waiting on <0x0000000795588ed0> (a java.lang.ref.ReferenceQueue$Lock)
    	at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:144)
    	- locked <0x0000000795588ed0> (a java.lang.ref.ReferenceQueue$Lock)
    	at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:165)
    	at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:216)
    
       Locked ownable synchronizers:
    	- None
    
    "Reference Handler" #2 daemon prio=10 os_prio=31 tid=0x00007f87a2013800 nid=0x5003 in Object.wait() [0x000070000e645000]
       java.lang.Thread.State: WAITING (on object monitor)
    	at java.lang.Object.wait(Native Method)
    	- waiting on <0x0000000795586bf8> (a java.lang.ref.Reference$Lock)
    	at java.lang.Object.wait(Object.java:502)
    	at java.lang.ref.Reference.tryHandlePending(Reference.java:191)
    	- locked <0x0000000795586bf8> (a java.lang.ref.Reference$Lock)
    	at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:153)
    
       Locked ownable synchronizers:
    	- None
    
    "VM Thread" os_prio=31 tid=0x00007f87a200d000 nid=0x3003 runnable 
    
    "GC task thread#0 (ParallelGC)" os_prio=31 tid=0x00007f87a180b800 nid=0x2507 runnable 
    
    "GC task thread#1 (ParallelGC)" os_prio=31 tid=0x00007f87a080b000 nid=0x2403 runnable 
    
    "GC task thread#2 (ParallelGC)" os_prio=31 tid=0x00007f879f00c800 nid=0x2203 runnable 
    
    "GC task thread#3 (ParallelGC)" os_prio=31 tid=0x00007f87a180c000 nid=0x2a03 runnable 
    
    "GC task thread#4 (ParallelGC)" os_prio=31 tid=0x00007f87a180c800 nid=0x5303 runnable 
    
    "GC task thread#5 (ParallelGC)" os_prio=31 tid=0x00007f87a180d800 nid=0x5203 runnable 
    
    "GC task thread#6 (ParallelGC)" os_prio=31 tid=0x00007f87a180e000 nid=0x2d03 runnable 
    
    "GC task thread#7 (ParallelGC)" os_prio=31 tid=0x00007f87a180e800 nid=0x2e03 runnable 
    
    "VM Periodic Task Thread" os_prio=31 tid=0x00007f87a210c000 nid=0x5503 waiting on condition 
    
    JNI global references: 320
    
    
    Found one Java-level deadlock:
    =============================
    "Thread-1":
      waiting for ownable synchronizer 0x00000007957e1a60, (a java.util.concurrent.locks.ReentrantLock$NonfairSync),
      which is held by "Thread-0"
    "Thread-0":
      waiting for ownable synchronizer 0x00000007957e1a90, (a java.util.concurrent.locks.ReentrantLock$NonfairSync),
      which is held by "Thread-1"
    
    Java stack information for the threads listed above:
    ===================================================
    "Thread-1":
    	at sun.misc.Unsafe.park(Native Method)
    	- parking to wait for  <0x00000007957e1a60> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)
    	at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
    	at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:836)
    	at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:870)
    	at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1199)
    	at java.util.concurrent.locks.ReentrantLock$NonfairSync.lock(ReentrantLock.java:209)
    	at java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:285)
    	at com.example.demo.service.Test2.lambda$main$1(Test2.java:29)
    	at com.example.demo.service.Test2$$Lambda$2/193064360.run(Unknown Source)
    	at java.lang.Thread.run(Thread.java:748)
    "Thread-0":
    	at sun.misc.Unsafe.park(Native Method)
    	- parking to wait for  <0x00000007957e1a90> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)
    	at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
    	at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:836)
    	at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:870)
    	at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1199)
    	at java.util.concurrent.locks.ReentrantLock$NonfairSync.lock(ReentrantLock.java:209)
    	at java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:285)
    	at com.example.demo.service.Test2.lambda$main$0(Test2.java:20)
    	at com.example.demo.service.Test2$$Lambda$1/94438417.run(Unknown Source)
    	at java.lang.Thread.run(Thread.java:748)
    
    Found 1 deadlock.
    

    可以看到发生了死锁。两个线程在互相等待对方释放锁。
    平时要注意加锁顺序和对结果的互相依赖,或者加锁增加超时时间。

    展开全文
  • 代码是这样的没实现死锁publicclassDeathLockTest{publicstaticvoidmain(String[]args){//TODOAuto-generatedmethodstubDeathRunnabler=newDeathRunnable();Threadt1=newThread(r,"t1...代码是这样的 没实现死锁...

    代码是这样的没实现死锁publicclassDeathLockTest{publicstaticvoidmain(String[]args){//TODOAuto-generatedmethodstubDeathRunnabler=newDeathRunnable();Threadt1=newThread(r,"t1...

    代码是这样的 没实现死锁

    public class DeathLockTest {

    public static void main(String[] args) {

    // TODO Auto-generated method stub

    DeathRunnable r=new DeathRunnable();

    Thread t1=new Thread(r,"t1");

    Thread t2=new Thread(r,"t2");

    t1.start();

    t2.start();

    }

    }

    class DeathRunnable implements Runnable{

    Object obj1=new Object();

    Object obj2=new Object();

    @Override

    public void run() {

    // TODO Auto-generated method stub

    if(Thread.currentThread().getName().equals("t1")){

    synchronized(obj2){

    System.out.println("线程1锁定obj1");

    }

    synchronized(obj1){

    System.out.println("线程1锁定obj2");

    }

    }else if(Thread.currentThread().getName().equals("t2")){

    synchronized(obj1){

    System.out.println("线程2锁定obj2");

    }

    synchronized(obj2){

    System.out.println("线程2锁定obj1");

    }

    }

    }

    }

    展开

    展开全文
  • Linux 死锁例子

    2021-05-15 04:30:38
    死锁是在编写多线程并发时候所需要考虑的问题,在多线程软件使用多个互斥锁来保护共享资源时,如果设计不合理会出现多个锁相互嵌套并且都在等待彼此的锁被释放,这样就会出现死锁现象,让系统挂起一直相互等待下去。...

    死锁是在编写多线程并发时候所需要考虑的问题,在多线程软件使用多个互斥锁来保护共享资源时,如果设计不合理会出现多个锁相互嵌套并且都在等待彼此的锁被释放,这样就会出现死锁现象,让系统挂起一直相互等待下去。下面给个例子说明这一现象:

    /* 头文件 */

    #include

    #include

    #include

    #include

    #include

    pthread_mutex_t mutex_one,mutex_two;

    pthread_mutex_t mutex;

    pthread_cond_t cond;

    void *thread_routine_one(void *arg)

    {

    pthread_cond_wait(&cond,&mutex);//确保two线程先运行

    printf("thread_routine_one: lock mutex_one!\n");

    pthread_mutex_lock(&mutex_one);

    printf("thread_routine_one: lock mutex_two!\n");

    pthread_mutex_lock(&mutex_two);//获取two锁,这个要等待two线程对two锁的释放

    sleep(1);

    printf("thread_routine_one: unlock mutex_two!\n");

    pthread_mutex_unlock(&mutex_two);

    printf("thread_routine_one: unlock mutex_one!\n");

    pthread_mutex_unlock(&mutex_one);

    return NULL;

    }

    void *thread_routine_two(void *arg)

    {

    printf("thread_routine_two: lock mutex_two!\n");

    pthread_mutex_lock(&mutex_two);//获取two锁

    pthread_cond_signal(&cond);//让one线程运行

    sleep(1);//休眠,让one可以先运行获取one锁

    printf("thread_routine_two: lock mutex_one!\n");

    pthread_mutex_lock(&mutex_one);//获取one锁,这个同样必须等待one线程多one锁的释放

    /**这时出现死锁现象了,在two线程要等待one线程对one锁的释放,同时two锁没有释放

    * 然而在one线程需要等待two线程对two锁的释放,然后才会对one锁的释放!出现相互等待的过程**/

    printf("thread_routine_two: unlock mutex_one!\n");

    pthread_mutex_unlock(&mutex_one);

    printf("thread_routine_two: unlock mutex_two!\n");

    pthread_mutex_unlock(&mutex_two);

    return NULL;

    }

    void main()

    {

    pthread_t pthread_one,pthread_two;

    pthread_mutex_init(&mutex_one,NULL);

    pthread_mutex_init(&mutex_two,NULL);

    pthread_mutex_init(&mutex,NULL);

    pthread_cond_init(&cond,NULL);

    pthread_create(&pthread_one,NULL,thread_routine_one,NULL);

    pthread_create(&pthread_two,NULL,thread_routine_two,NULL);

    while(1)

    sleep(1);

    }

    展开全文
  • MySQL死锁例子

    2021-02-04 09:57:38
    一、mysql死锁 比如2个事务,事务A、事务B,都查询id=74和id=78的数据,并加锁 事务A,select * from t where id=74for update,对id=74数据加锁 然后,事务B,select * from t where id=78for update,对id=78...
  • java写的一个死锁例子

    2021-03-09 04:44:21
    java写的一个死锁例子public class DeadLock {/*** @param args*/public static void main(String[] args) {// TODO Auto-generated method stubfinal Object resource1 = "resource1";final Object resource2 = ...
  • Java死锁的简单例子

    2021-04-17 10:08:04
    Java死锁的简单例子两个线程互相占有对方需要的资源而不释放,便形成了死锁。代码如下:Program.java/*** 程序类* @author michael**/public class Program implements Runnable {//两个静态的资源public static ...
  • #死锁核心思想 死锁产生的根本原因就是多个进程之间互相占用了对方的资源不释放,导致所有进程都无法继续推进下去的一种状态 如图所示,进程1拥有 A ,但是它需要 B 才能继续执行下去,正好这个时候进程2在持有 B ...
  • Java多线程--死锁例子

    2021-03-05 11:29:00
    * @描述模拟死锁 * * 形成死锁的四个必要条件是什么 * * 1.互斥条件:线程(进程)对于所分配到的资源具有排它性,即一个资源只能被一个线程(进程)占用,直到被该线程(进程)释放 * 2.请求与保持条件:一个线程...
  • 一个死锁例子.

    2021-05-17 19:16:40
    打开命令行, 运行jconsole, 选择本地刚才启动的进程, 然后进入线程Tab页,可以查看到当前运行的所有线程, 点击"检测到死锁"可以查看到发生死锁的线程. 来自 “ ITPUB博客 ” ,链接:...
  • mysql sleep 死锁例子

    2021-01-27 09:36:19
    表结构 CREATE TABLE `orders` ( `order_id` int(11) NOT NULL, `order_addr` varchar(255) DEFAULT NULL ) ENGINE=InnoDB DEFAULT CHARSET=utf8;... 先执行第一条,再执行第二条,第二条成功,第一条会出现死锁
  • 由于InnoDB预设是Row-LevelLock,所以只有「明确」的指定主键,MySQL才会...举个例子:假设有个表单products,里面有id跟name二个栏位,id是主键。例1:(明确指定主键,并且有此笔资料,rowlock)SELECT*FROMproducts...
  • 代码:publicclassTestDeadLockimplementsRunnable{ publicintflag=1;...上边这部分代码是Java的一个线程死锁例子,哪位高手帮忙理解一下哪里体现出来的死锁。。。分析一下代码,非常感谢! 展开
  • 死锁产生的四个必要条件。1>互斥使用,即当资源被一个线程使用(占有)时,别的线程不能使用2>不可抢占,资源请求者不能强制从资源占有者手中夺取资源,资源只能由资源占有者主动释放。3>请求和保持,即当...
  • 死锁例子

    2021-11-14 22:45:45
    什么是死锁? 多个线程互相抱着对方的资源,然后形成僵持 产生死锁的四个必要条件: (1)互斥条件:一个资源每次只能被一个进程使用 (2)请求与保持条件:一个进程因请求资源而阻塞时,对已获得的资源保持不放 (3...
  • 死锁产生后mysql根据两个事务的权重,事务2的权重更小,被选为死锁的牺牲者,rollback。 T2 rollback 之后T1成功获取了锁执行成功 Mysql 官方解释 Deadlock occurs here because client A needs an X lock to ...
  • 死锁的概念 什么是死锁? 程序流程无法继续推进卡死的状态 死锁产生条件 1.互斥条件:我接了锁,别人就不能加锁 2.不可剥夺条件:我加了锁,只有我能解 3.请求与保持条件:加了A锁请求B锁,请求不到B锁 ,A锁不...
  • 文章目录死锁建表客户端一客户端二分析 死锁 所谓死锁就是必须发生在下面的四个必要条件 ...比如下面这个例子 建表 CREATE TABLE `test1` ( `id` int(11) NOT NULL AUTO_INCREMENT, `name` varch
  • 各位看官们,大家好,上一回中咱们说的是线程同步之互斥量的例子,这一回咱们说的例子是:线程死锁。闲话休提,言归正转。让我们一起talk c栗子吧!我们在前面章回中介绍互斥量相关的函数时提到过死锁,不过当时没有...
  • 接到上级一个生产环境MySQL死锁日志信息文件,需要找出原因并解决问题。我将死锁日志部分贴出如下:在mysql中使用命令:SHOW ENGINE INNODB STATUS;总能获取到最近一些问题信息,通过搜索deadlock 关键字即可找到...
  • 操作系统---死锁

    2021-01-18 21:14:15
    操作系统---死锁1. 引入2. 死锁定义3. 产生死锁的必要条件4. 处理死锁的基本方法4.1. 死锁的预防4.2.死锁的避免5. 预防死锁的方法5.1破坏“互斥”条件:5.2破坏“不可抢占”条件5.3...日常生活中有关死锁例子(交通
  • 万向节死锁 gimbal lock

    2021-01-14 11:03:26
    【所谓的死锁,仅是在一个操作单元,即XYZ组成的任意一个次序中出现了无法控制的现象,如上面飞机失灵的情况,我们可以继续操作X轴(红圈)来调整飞机的仰视和俯视,这时飞机又可以回到水平飞行的正常轨道上来了】 ...
  • 创建表 CREATE TABLE `test1` ( `id` int(11) NOT NULL AUTO_INCREMENT, `name` varchar(10) NOT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=1 ... 这两个事务相互等待对方的排它锁释放,如此出现了死锁
  • 测试环境:MySQL 5.7.26创建测试表:createtablet5(idint);QueryOK,0rowsaffected(0.01sec)插入测试...QueryOK,1rowaffected(0.00sec)模拟死锁过程:会话1申请X锁,等待会话2,会话2申请X锁,等待会话1。会话2死锁...
  • 这篇文章主要介绍了c++多线程之死锁的发生的情况解析(包含两个归纳,6个示例),需要的朋友可以参考下 一、死锁会在什么情况发生 1、假设有如下代码 mutex;//代表一个全局互斥对象 voidA() { mutex.lock(); ...
  • 操作系统中,银行家算法是避免死锁的一种重要算法。 本文针对《计算机操作系统(第四版)》(汤小丹)p123页的问题:**如果在银行家算法中把P0发出的请求向量改为Request0(0,1,0),系统是否能将资源分配给它,请读者...
  • Linux驱动 之自旋锁、死锁学习记录: 内核当发生访问资源冲突的时候,可以有两种锁的解决方案选择: 一种是原地等待。 一种是挂起当前进程,调度其他进程执行(睡眠)。 linux 内核中最常见的锁就是Spinlock自旋锁,...

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