如果内部发生异常，锁定的对象是否保持锁定状态? [英] Does a locked object stay locked if an exception occurs inside it?

问题描述

在一个 c# 线程应用程序中，如果我要锁定一个对象，比如说一个队列，如果发生异常，该对象会保持锁定状态吗?这是伪代码:

In a c# threading app, if I were to lock an object, let us say a queue, and if an exception occurs, will the object stay locked? Here is the pseudo-code:

int ii;
lock(MyQueue)
{
   MyClass LclClass = (MyClass)MyQueue.Dequeue();
   try
   {
      ii = int.parse(LclClass.SomeString);
   }
   catch
   {
     MessageBox.Show("Error parsing string");
   }
}

据我所知，catch 之后的代码不会执行 - 但我一直想知道锁是否会被释放.

As I understand it, code after the catch doesn't execute - but I have been wondering if the lock will be freed.

推荐答案

First;你考虑过 TryParse 吗?

First; have you considered TryParse?

in li;
if(int.TryParse(LclClass.SomeString, out li)) {
    // li is now assigned
} else {
    // input string is dodgy
}

锁会因为两个原因被释放；首先，lock本质上是:

The lock will be released for 2 reasons; first, lock is essentially:

Monitor.Enter(lockObj);
try {
  // ...
} finally {
    Monitor.Exit(lockObj);
}

第二；您捕获并且不重新抛出内部异常，因此 lock 从未真正看到异常.当然，您在 MessageBox 期间持有锁，这可能是一个问题.

Second; you catch and don't re-throw the inner exception, so the lock never actually sees an exception. Of course, you are holding the lock for the duration of a MessageBox, which might be a problem.

因此它将在除最致命的灾难性不可恢复异常之外的所有异常中释放.

So it will be released in all but the most fatal catastrophic unrecoverable exceptions.

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