Java线程生命周期图文详细讲解
健鑫. 人气:0线程的状态
New
- 表示线程已创建,没启动的状态
- 此时已经做了一些准备工作,还没有执行run方法中代码
Runnable
- 调用start方法之后的状态,表示可运行状态(不一定正在运行,因为调用start方法之后不一定立即运行)
- 如果线程拿到CPU资源,但是突然资源被抢走,这个线程依然处于Runnable
Blocked
- 线程进入到被synchronized修饰的代码块时,该锁已经被其他线程拿走,此时该线程处于Blocked
- Blocked只针对synchronized
Waiting
- 没有设置时间参数的Object.wait方法可使线程状态变为waiting
Timed Waiting
- 相对Waiting,有了时间参数
Terminated
- 执行完毕
- run方法正常执行完毕
- 或者出现了一个没有被捕获的异常终止了run方法
代码演示
- 展示线程的New、Runnable、Terminated状态
- 线程刚被new处于NEW状态
- 调用start方法处于RUNNABLE状态
- 程序正在执行处于RUNNABLE状态而不是RUNNING
- 程序结束处于TERMINATED状态
public class NewRunnableTerminated implements Runnable { public static void main(String[] args) { Thread thread = new Thread(new NewRunnableTerminated()); // 打印线程状态 // New System.out.println(thread.getState()); thread.start(); // Runnable System.out.println(thread.getState()); // try { // Thread.sleep(100); // } catch (InterruptedException e) { // e.printStackTrace(); // } // Runnable System.out.println(thread.getState()); try { Thread.sleep(100); } catch (InterruptedException e) { e.printStackTrace(); } // TERMINATED System.out.println(thread.getState()); } @Override public void run() { for (int i = 0; i < 10000; i++) { System.out.println(i); } } } /* * NEW RUNNABLE RUNNABLE * TERMINATED * */
- 演示waiting、Blocked、Timed Waiting
- 中间频繁调用sleep方法是防止代码执行太快,达不到应有的效果
- 线程被调用sleep,处于TIMED_WAITING
- 当一个线程执行synchronized内的代码,另一个线程也要执行则该线程处于BLOCKED
- 线程执行wait方法,处于WAITING
public class BlockWaitingTimedWaiting implements Runnable{ public static void main(String[] args) { BlockWaitingTimedWaiting blockWaitingTimedWaiting = new BlockWaitingTimedWaiting(); Thread thread1 = new Thread(blockWaitingTimedWaiting); thread1.start(); Thread thread2 = new Thread(blockWaitingTimedWaiting); thread2.start(); try { Thread.sleep(100); } catch (InterruptedException e) { e.printStackTrace(); } System.out.println(thread1.getState()); try { Thread.sleep(100); } catch (InterruptedException e) { e.printStackTrace(); } System.out.println(thread2.getState()); try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } System.out.println(thread1.getState()); } @Override public void run() { syn(); } private synchronized void syn() { try { Thread.sleep(1000); wait(); } catch (InterruptedException e) { e.printStackTrace(); } } } /* * TIMED_WAITING BLOCKED WAITING * */
阻塞状态
- 一般而言,Blocked、Waiting、Timed_waiting都被称之为阻塞状态
- 在阻塞状态下,什么时候可以继续执行是不受控制的
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