英文:
Why deadlock is not prevented upon detection with a runtime exception by the JVM?
问题
Java可以检测即将发生的死锁（至少在某些情况下）
例如，考虑以下情况：
线程A获取锁A
线程B获取锁B
线程A试图获取锁B - 并被阻塞
线程B试图获取锁A - 并无限期阻塞
在最后一种情况下，Java虚拟机知道它将陷入死锁（因为它知道哪个线程持有哪个锁）。
因此，我的问题是，为什么Java虚拟机在即将导致死锁的锁获取时不会抛出运行时错误，从而终止线程（就像任何其他未处理的异常一样），并释放它的锁，就像正常情况下一样。
例如，在数据库中，如果事务尝试锁定某个记录，并且数据库确定将发生死锁，那么该事务将被中止。
同样的原则也可以应用于线程，那么为什么不呢？
英文:
Java can detect a deadlock that is about to happen (or at least in some cases)
For example, consider the following:
Thread A acquires Lock A
Thread B acquires Lock B
Thread A tries to acquire Lock B - and blocks
Thread B tries to acquire Lock A - and blocks indefinitely
In the last statement, the JVM knows that it will end up in a deadlock (because it knows which thread holds which lock).
So my question is, why the JVM doesn't throw a runtime error upon the lock acquisition that will cause a deadlock, resulting in termination of the thread (like any other unhandled exception), and releasing its locks, again, like normal.
For example, in a database, if a transaction tries to lock some record and the DB figures out it will be deadlocked, that transaction is aborted.
The same can be applied to threads, so why not?
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