如何调试 ConcurrentModificationException? [英] How to debug ConcurrentModificationException?

问题描述

我遇到了 ConcurrentModificationException 并且通过查看它我看不出它发生的原因；抛出异常的区域和所有修改集合的地方都被

I encountered ConcurrentModificationException and by looking at it I can't see the reason why it's happening; the area throwing the exception and all the places modifying the collection are surrounded by

synchronized (this.locks.get(id)) {
  ...
} // locks is a HashMap<String, Object>;

我试图捕获讨厌的线程，但我所能确定的(通过在异常中设置断点)是抛出线程拥有监视器，而另一个线程(程序中有两个线程)休眠.

I tried to catch the the pesky thread but all I could nail (by setting a breakpoint in the exception) is that the throwing thread owns the monitor while the other thread (there are two threads in the program) sleeps.

我应该如何进行?当您遇到类似的线程问题时，您通常会怎么做?

How should I proceed? What do you usually do when you encounter similar threading issues?

推荐答案

可能与同步块无关.ConcurrentModificationException 经常发生在您在迭代集合元素时修改集合.

It may have nothing to do with the synchronization block. ConcurrentModificationExceptions often occur when you're modifying a collection while you are iterating over its elements.

List<String> messages = ...;
for (String message : messages) {
    // Prone to ConcurrentModificationException
    messages.add("A COMPLETELY NEW MESSAGE");
}

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