java - java上 "BLOCKED"和 "TIMED_WAITING"的区别

Question

我们的 tomcat 没有响应任何请求。当我使用“jstack pid”打印堆栈信息时，我得到了以下信息。我发现它在“Thread.sleep(long)”上被阻止。我认为应该是“TIMED_WAITING”。为什么？

Thread 24836: (state = BLOCKED)
- java.lang.Thread.sleep(long) @bci=0 (Compiled frame; information may be imprecise)
- com.lagou.base.proxy.MasterTemplateContainer.checkMaster(org.springframework.orm.hibernate3.HibernateTemplate) @bci=128, line=221 (Compiled frame)
- com.lagou.base.proxy.MasterTemplateContainer.access$1(com.lagou.base.proxy.MasterTemplateContainer, org.springframework.orm.hibernate3.HibernateTemplate) @bci=2, line=185 (Interpreted frame)
- com.lagou.base.proxy.MasterTemplateContainer$2.run() @bci=8, line=134 (Interpreted frame)
- java.util.concurrent.ThreadPoolExecutor.runWorker(java.util.concurrent.ThreadPoolExecutor$Worker) @bci=95, line=1145 (Interpreted frame)
- java.util.concurrent.ThreadPoolExecutor$Worker.run() @bci=5, line=615 (Interpreted frame)
- java.lang.Thread.run() @bci=11, line=744 (Interpreted frame)


Thread 24835: (state = BLOCKED)
- java.lang.Thread.sleep(long) @bci=0 (Compiled frame; information may be imprecise)
- com.lagou.base.proxy.MasterTemplateContainer.checkMaster(org.springframework.jdbc.core.JdbcTemplate) @bci=128, line=177 (Compiled frame)
- com.lagou.base.proxy.MasterTemplateContainer.access$0(com.lagou.base.proxy.MasterTemplateContainer, org.springframework.jdbc.core.JdbcTemplate) @bci=2, line=141 (Interpreted frame)
- com.lagou.base.proxy.MasterTemplateContainer$1.run() @bci=8, line=125 (Interpreted frame)
- java.util.concurrent.ThreadPoolExecutor.runWorker(java.util.concurrent.ThreadPoolExecutor$Worker) @bci=95, line=1145 (Interpreted frame)
- java.util.concurrent.ThreadPoolExecutor$Worker.run() @bci=5, line=615 (Interpreted frame)
- java.lang.Thread.run() @bci=11, line=744 (Interpreted frame)

我的代码:

private void checkMaster(HibernateTemplate hdao) {
    int loopErrors = errorTimes;
    int loopSuccess = successTimes;
    while(true) {
        boolean success = true;
        try {
            if(hdao == null){
                success = false;
                continue;
            }
            success = checkMasterStatusOnce(hdao);//try access database to get the status
        } catch (Exception e1) {
            logger.error("",e1);
            success = false;
        }

    try {
        Thread.sleep(checkInterval);
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
}
}

该方法被调用

public void check() {
    for (final JdbcTemplate jdao : jdbcTemplates) {
        threadPoolExecutor.execute(new Runnable(){
            public void run() {
                checkMaster(jdao);
            }
        });
    }
}

Answer 1

你是对的，Thread的线程状态方法内部Thread.sleep应该是TIMED_WAITING .

引用authoritative source :

public static final Thread.State TIMED_WAITING

Thread state for a waiting thread with a specified waiting time. A thread is in the timed waiting state due to calling one of the following methods with a specified positive waiting time:

• Thread.sleep
• Object.wait with timeout
• Thread.join with timeout
• LockSupport.parkNanos
• LockSupport.parkUntil

我测试了 1.6 范围内的多个 Java 版本(Oracle 的实现)至1.8 ，包含在内，并且都显示了 Thread.sleep 内报告线程的正确行为。与国家TIMED_WAITING .

考虑the following statement about Thread.sleep() 也很重要:

… The thread does not lose ownership of any monitors.

因此，由于线程不会失去监视器的所有权，因此它不会重新获取监视器。所以它不应该在 Thread.State.BLOCKED 中.

因此，您要么使用不同的 JVM/JRE 实现，要么使用修改后的 Thread类，也许它已在运行时通过 Instrumentation 进行了修改。无论哪种情况，您在问题中提供的信息都不足以进一步缩小您的问题范围。

了解 jstack 的版本也很有用。你使用的输出格式与我得到的格式不同。也许是打印状态的工具错误......