.net 多线程 lock锁的问题
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一个一直让我不明白的地方
statie int i=1;
void s()
lock(this)
i+=1;
response.wirte(i.ToString());
上面是我手写的一点代码 其实意思很简单 就是我现在有一个静态变量i
用10个线程来执行一个方法 每执行完这个方法 就要给i加1 当i到了1000的时候 就自动 把10个线程停止
可是我这样写 i总是有重复 或者 有的没有 我觉得应该是 lock那里的问题 是不是我写错了？为什么总锁不住i?
说简单一点吧
Thread[] td = new Thread[5];
for (int i = 0; i < td.Length; i++)
td[i] = new Thread(new ThreadStart(AgentIPjc));
td[i].Start();
public static void AgentIPjc()
while (true)
string[] _url = null;
lock (s)
if (_i >= _strs.Length)
Thread.CurrentThread.Abort();
// break;
_url = _strs[_i].Split(':');
_i += 1;
if (Helper.Request_Source_Proxy(_url[0], _url[1]))
if (_sb.Length > 0)
_sb.Append("|");
_sb.Append(_url[0] + ":" + _url[1]);
在AgentIPjc方法里的局部变量url
第二个线程 会不会修改第一个线程中的url
因为lock (this) 所以就会有10个锁变量，结果和不加锁的效果相同。
可以考虑static object slock = new object () ;
lock (slock)
因为对static变量访问，定义static锁变量比较贴切。 参考技术A 写法应该是没问题的
不过，建议在 WINFORM 或 console 程序中测试， ASP.NET 中不宜测试多线程 参考技术B static object i;
lock(i)
i = (int)i + 1;
参考技术C 我去死。本回答被提问者采纳 参考技术D 帮你解决了
多线程中的锁的几种用法总结
一、ReentrantLock
1 package com.ietree.basicskill.mutilthread.lock; 2 3 import java.util.concurrent.locks.Lock; 4 import java.util.concurrent.locks.ReentrantLock; 5 6 /** 7 * Created by Administrator on 2017/5/17. 8 */ 9 public class UseReentrantLock { 10 11 private Lock lock = new ReentrantLock(); 12 13 public void method1(){ 14 try { 15 lock.lock(); 16 System.out.println("当前线程:" + Thread.currentThread().getName() + "进入method1.."); 17 Thread.sleep(1000); 18 System.out.println("当前线程:" + Thread.currentThread().getName() + "退出method1.."); 19 Thread.sleep(1000); 20 } catch (InterruptedException e) { 21 e.printStackTrace(); 22 } finally { 23 24 lock.unlock(); 25 } 26 } 27 28 public void method2(){ 29 try { 30 lock.lock(); 31 System.out.println("当前线程:" + Thread.currentThread().getName() + "进入method2.."); 32 Thread.sleep(2000); 33 System.out.println("当前线程:" + Thread.currentThread().getName() + "退出method2.."); 34 Thread.sleep(1000); 35 } catch (InterruptedException e) { 36 e.printStackTrace(); 37 } finally { 38 39 lock.unlock(); 40 } 41 } 42 43 public static void main(String[] args) { 44 45 final UseReentrantLock ur = new UseReentrantLock(); 46 Thread t1 = new Thread(new Runnable() { 47 @Override 48 public void run() { 49 ur.method1(); 50 ur.method2(); 51 } 52 }, "t1"); 53 54 t1.start(); 55 try { 56 Thread.sleep(10); 57 } catch (InterruptedException e) { 58 e.printStackTrace(); 59 } 60 //System.out.println(ur.lock.getQueueLength()); 61 } 62 63 }
二、ReentrantReadWriteLock
1 package com.ietree.basicskill.mutilthread.lock; 2 3 import java.util.concurrent.locks.ReentrantReadWriteLock; 4 5 /** 6 * Created by Administrator on 2017/5/17. 7 */ 8 public class UseReentrantReadWriteLock { 9 10 private ReentrantReadWriteLock rwLock = new ReentrantReadWriteLock(); 11 private ReentrantReadWriteLock.ReadLock readLock = rwLock.readLock(); 12 private ReentrantReadWriteLock.WriteLock writeLock = rwLock.writeLock(); 13 14 public void read(){ 15 try { 16 readLock.lock(); 17 System.out.println("当前线程:" + Thread.currentThread().getName() + "进入..."); 18 Thread.sleep(3000); 19 System.out.println("当前线程:" + Thread.currentThread().getName() + "退出..."); 20 } catch (Exception e) { 21 e.printStackTrace(); 22 } finally { 23 readLock.unlock(); 24 } 25 } 26 27 public void write(){ 28 try { 29 writeLock.lock(); 30 System.out.println("当前线程:" + Thread.currentThread().getName() + "进入..."); 31 Thread.sleep(3000); 32 System.out.println("当前线程:" + Thread.currentThread().getName() + "退出..."); 33 } catch (Exception e) { 34 e.printStackTrace(); 35 } finally { 36 writeLock.unlock(); 37 } 38 } 39 40 public static void main(String[] args) { 41 42 final UseReentrantReadWriteLock urrw = new UseReentrantReadWriteLock(); 43 44 Thread t1 = new Thread(new Runnable() { 45 @Override 46 public void run() { 47 urrw.read(); 48 } 49 }, "t1"); 50 Thread t2 = new Thread(new Runnable() { 51 @Override 52 public void run() { 53 urrw.read(); 54 } 55 }, "t2"); 56 Thread t3 = new Thread(new Runnable() { 57 @Override 58 public void run() { 59 urrw.write(); 60 } 61 }, "t3"); 62 Thread t4 = new Thread(new Runnable() { 63 @Override 64 public void run() { 65 urrw.write(); 66 } 67 }, "t4"); 68 69 // t1.start(); 70 // t2.start(); 71 72 // t1.start(); // R 73 // t3.start(); // W 74 75 t3.start(); 76 t4.start(); 77 } 78 }
三、Condition
1 package com.ietree.basicskill.mutilthread.lock; 2 3 import java.util.concurrent.locks.Condition; 4 import java.util.concurrent.locks.Lock; 5 import java.util.concurrent.locks.ReentrantLock; 6 7 /** 8 * Created by Administrator on 2017/5/17. 9 */ 10 public class UseCondition { 11 private Lock lock = new ReentrantLock(); 12 private Condition condition = lock.newCondition(); 13 14 public void method1(){ 15 try { 16 lock.lock(); 17 System.out.println("当前线程：" + Thread.currentThread().getName() + "进入等待状态.."); 18 Thread.sleep(3000); 19 System.out.println("当前线程：" + Thread.currentThread().getName() + "释放锁.."); 20 condition.await(); // Object wait 21 System.out.println("当前线程：" + Thread.currentThread().getName() +"继续执行..."); 22 } catch (Exception e) { 23 e.printStackTrace(); 24 } finally { 25 lock.unlock(); 26 } 27 } 28 29 public void method2(){ 30 try { 31 lock.lock(); 32 System.out.println("当前线程：" + Thread.currentThread().getName() + "进入.."); 33 Thread.sleep(3000); 34 System.out.println("当前线程：" + Thread.currentThread().getName() + "发出唤醒.."); 35 condition.signal(); //Object notify 36 } catch (Exception e) { 37 e.printStackTrace(); 38 } finally { 39 lock.unlock(); 40 } 41 } 42 43 public static void main(String[] args) { 44 45 final UseCondition uc = new UseCondition(); 46 Thread t1 = new Thread(new Runnable() { 47 @Override 48 public void run() { 49 uc.method1(); 50 } 51 }, "t1"); 52 Thread t2 = new Thread(new Runnable() { 53 @Override 54 public void run() { 55 uc.method2(); 56 } 57 }, "t2"); 58 t1.start(); 59 60 t2.start(); 61 } 62 }
四、ManyCondition
1 package com.ietree.basicskill.mutilthread.lock; 2 3 import java.util.concurrent.locks.Condition; 4 import java.util.concurrent.locks.ReentrantLock; 5 6 /** 7 * Created by Administrator on 2017/5/17. 8 */ 9 public class UseManyCondition { 10 private ReentrantLock lock = new ReentrantLock(); 11 private Condition c1 = lock.newCondition(); 12 private Condition c2 = lock.newCondition(); 13 14 public void m1(){ 15 try { 16 lock.lock(); 17 System.out.println("当前线程：" +Thread.currentThread().getName() + "进入方法m1等待.."); 18 c1.await(); 19 System.out.println("当前线程：" +Thread.currentThread().getName() + "方法m1继续.."); 20 } catch (Exception e) { 21 e.printStackTrace(); 22 } finally { 23 lock.unlock(); 24 } 25 } 26 27 public void m2(){ 28 try { 29 lock.lock(); 30 System.out.println("当前线程：" +Thread.currentThread().getName() + "进入方法m2等待.."); 31 c1.await(); 32 System.out.println("当前线程：" +Thread.currentThread().getName() + "方法m2继续.."); 33 } catch (Exception e) { 34 e.printStackTrace(); 35 } finally { 36 lock.unlock(); 37 } 38 } 39 40 public void m3(){ 41 try { 42 lock.lock(); 43 System.out.println("当前线程：" +Thread.currentThread().getName() + "进入方法m3等待.."); 44 c2.await(); 45 System.out.println("当前线程：" +Thread.currentThread().getName() + "方法m3继续.."); 46 } catch (Exception e) { 47 e.printStackTrace(); 48 } finally { 49 lock.unlock(); 50 } 51 } 52 53 public void m4(){ 54 try { 55 lock.lock(); 56 System.out.println("当前线程：" +Thread.currentThread().getName() + "唤醒.."); 57 c1.signalAll(); 58 } catch (Exception e) { 59 e.printStackTrace(); 60 } finally { 61 lock.unlock(); 62 } 63 } 64 65 public void m5(){ 66 try { 67 lock.lock(); 68 System.out.println("当前线程：" +Thread.currentThread().getName() + "唤醒.."); 69 c2.signal(); 70 } catch (Exception e) { 71 e.printStackTrace(); 72 } finally { 73 lock.unlock(); 74 } 75 } 76 77 public static void main(String[] args) { 78 79 80 final UseManyCondition umc = new UseManyCondition(); 81 Thread t1 = new Thread(new Runnable() { 82 @Override 83 public void run() { 84 umc.m1(); 85 } 86 },"t1"); 87 Thread t2 = new Thread(new Runnable() { 88 @Override 89 public void run() { 90 umc.m2(); 91 } 92 },"t2"); 93 Thread t3 = new Thread(new Runnable() { 94 @Override 95 public void run() { 96 umc.m3(); 97 } 98 },"t3"); 99 Thread t4 = new Thread(new Runnable() { 100 @Override 101 public void run() { 102 umc.m4(); 103 } 104 },"t4"); 105 Thread t5 = new Thread(new Runnable() { 106 @Override 107 public void run() { 108 umc.m5(); 109 } 110 },"t5"); 111 112 t1.start(); // c1 113 t2.start(); // c1 114 t3.start(); // c2 115 116 117 try { 118 Thread.sleep(2000); 119 } catch (InterruptedException e) { 120 e.printStackTrace(); 121 } 122 123 t4.start(); // c1 124 try { 125 Thread.sleep(2000); 126 } catch (InterruptedException e) { 127 e.printStackTrace(); 128 } 129 t5.start(); // c2 130 131 } 132 }
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