Question

  "dashboardRefreshContainer-8" - Thread t@1384
   java.lang.Thread.State: RUNNABLE
    at sun.util.calendar.ZoneInfo.getLastRule(ZoneInfo.java:638)
    - locked <4d70153e> (a sun.util.calendar.ZoneInfo)
    at sun.util.calendar.ZoneInfo.getOffsets(ZoneInfo.java:275)
    at sun.util.calendar.ZoneInfo.getOffsets(ZoneInfo.java:225)
    at java.util.GregorianCalendar.computeFields(GregorianCalendar.java:2024)
    at java.util.GregorianCalendar.computeFields(GregorianCalendar.java:1996)
    at java.util.Calendar.setTimeInMillis(Calendar.java:1109)
    at java.util.Calendar.setTime(Calendar.java:1075)

"TP-Processor38" - Thread t@158
   java.lang.Thread.State: RUNNABLE
    at sun.util.calendar.ZoneInfo.getLastRule(ZoneInfo.java:638)
    - locked <4d70153e> (a sun.util.calendar.ZoneInfo)
    at sun.util.calendar.ZoneInfo.getOffsets(ZoneInfo.java:275)
    at sun.util.calendar.ZoneInfo.getOffsets(ZoneInfo.java:225)
    at java.util.GregorianCalendar.computeFields(GregorianCalendar.java:2024)
    at java.util.GregorianCalendar.computeFields(GregorianCalendar.java:1996)
    at java.util.Calendar.setTimeInMillis(Calendar.java:1109)
    at java.util.Calendar.setTime(Calendar.java:1075)

线程都是Runnable，它们持有相同的锁。两个线程都可以锁定相同的地址，而它们都是RUNNABLE吗？这是一个JRE错误吗？

Answer 1

问题仅存在于线程转储中。实际上，在任何时间点，锁只由一个线程保持。但是，线程转储显示两个具有相同锁定的不同线程，因为它不是原子的。

使用以下程序可以轻松复制该行为：

public class Test {
    public static void main(String[] args) {
        Runnable runnable = new Runnable() {
            public void run() {
                for (;;) {
                    synchronized (this) { }
                }
            }
        };
        new Thread(runnable).start();
        new Thread(runnable).start();
    }
}

多个线程持有相同的锁？

1 个答案: