物联网网站开发,a5做网站,织梦网站安装出现404 not found,旅游网站系统文章详细内容来自#xff1a;线程数突增#xff01;领导#xff1a;谁再这么写就滚蛋#xff01;
下面是看完后文章的#xff0c;一个总结
线程池的使用不规范#xff0c;导致程序中线程数不下降#xff0c;线程数量大。
临时变量的接口#xff0c;通过下面简单的线…文章详细内容来自线程数突增领导谁再这么写就滚蛋
下面是看完后文章的一个总结
线程池的使用不规范导致程序中线程数不下降线程数量大。
临时变量的接口通过下面简单的线程池执行
private static void threadDontGcDemo(){ExecutorService executorService Executors.newFixedThreadPool(10);executorService.submit(() - {System.out.println(111);});}
线程不被GC回收主要是线程池的gc root还是有可达路径的。这里讲个冷知识这里的线程池的gc root是线程具体的gc路径是thread-workers-线程池
如果临时采用线程池需要 手动设置线程池的shutdown下面写法:
private static void threadDontGcDemo(){ExecutorService executorService Executors.newFixedThreadPool(10);executorService.submit(() - {System.out.println(111);});executorService.shutdown();}
原理是shutdown方法是遍历所有线程并且调用线程的interrupt()方法通知线程中断当worker进行getTask()时让处于wait的线程打断抛出异常workers捕获该workerworkers.remove(w)然后将worker移除workers这样gc root就不可达了便会被GC掉。
也就是说线程池的shutdownnow方法调用interruptIdleWorkers去对线程对象interrupt是为了让处于waiting或者是time_waiting的线程抛出异常。
总结为 线程池调用shutdownnow方法是为了调用worker对象的interrupt方法来打断那些沉睡中的线程waiting或者time_waiting状态使其抛出异常 线程池会把抛出异常的worker对象从workers集合中移除引用此时被移除的worker对象因为没有到达gc root的路径已经可以被gc掉了 等到workers对象空了并且当前tomcat线程也结束此时线程池对象也可以被gc掉整个线程池对象成功释放 Async 线程控制
如果不进行线程控制则异步执行程序越多会导致线程用尽。
一种方式是全局配置所有的异步线程共用线程池
Configuration
public class AsyncConfig implements AsyncConfigurer {Overridepublic Executor getAsyncExecutor() {ThreadPoolTaskExecutor executor new ThreadPoolTaskExecutor();executor.setCorePoolSize(10);executor.setMaxPoolSize(20);executor.setQueueCapacity(100);return executor;}Overridepublic AsyncUncaughtExceptionHandler getAsyncUncaughtExceptionHandler() {return new CustomAsyncExceptionHandler();}Overridepublic Integer getAsyncExecutor() {return 30; // 单位为秒}}
另外一种是Async标签指定使用的线程池名称
Configuration
EnableAsync
public class TaskExcutorConfig {Bean(taskExecutor)public Executor taskExecutro() {ThreadPoolTaskExecutor taskExecutor new ThreadPoolTaskExecutor();taskExecutor.setCorePoolSize(30);taskExecutor.setMaxPoolSize(50);taskExecutor.setQueueCapacity(200);taskExecutor.setKeepAliveSeconds(60);taskExecutor.setThreadNamePrefix(taskExecutor--);taskExecutor.setWaitForTasksToCompleteOnShutdown(true);taskExecutor.setAwaitTerminationSeconds(60);return taskExecutor;}Bean(commonExecutor)public Executor commonTaskExecutro() {ThreadPoolTaskExecutor taskExecutor new ThreadPoolTaskExecutor();taskExecutor.setCorePoolSize(50);taskExecutor.setMaxPoolSize(100);taskExecutor.setQueueCapacity(2000);taskExecutor.setKeepAliveSeconds(60);taskExecutor.setThreadNamePrefix(commonExecutor--);taskExecutor.setWaitForTasksToCompleteOnShutdown(true);taskExecutor.setAwaitTerminationSeconds(60);return taskExecutor;}Bean(notificationExecutor)public Executor notificationExecutor() {ThreadPoolTaskExecutor taskExecutor new ThreadPoolTaskExecutor();taskExecutor.setCorePoolSize(30);taskExecutor.setMaxPoolSize(60);taskExecutor.setQueueCapacity(2000);taskExecutor.setKeepAliveSeconds(60);taskExecutor.setThreadNamePrefix(notificationExecutor--);taskExecutor.setWaitForTasksToCompleteOnShutdown(true);taskExecutor.setAwaitTerminationSeconds(60);return taskExecutor;}
}
使用时标明
Async(commonExecutor)
