我得到分段错误而不是异常 [英] I get a segmentation fault instead of an exception

问题描述

在下面的代码中，在第一次迭代中出现异常，在第二次迭代中出现分段错误，没有打印任何错误消息.似乎没有捕获到异常:

In the following code, at the first iteration I get an exception, and at the second one I get a segmentation fault with no error message printed. It seems the exception is not caught:

int i = 0;
while(i++ < 10)
{
   try {
      cout << "Iteration: " << i << endl;
      // Code...
      cout << "OK" << endl;
   }
   catch(...)
   {
      cerr << "Error message" << endl;
      continue;
   }
}

Output:
Iteration 1
Error message
Iteration 2
Segmentation fault

这是正常的，还是真的有问题?

Is it normal, or there is something really wrong going on?

如果它应该是相关的，在那个代码块中我重置了一个 MySQL 连接，当我检查连接是否关闭时会生成异常.

In case it should be relevant, in that code block I reset a MySQL connection, and the exception is generated when I check if the connection is closed.

谢谢.

平台:
Linux - OpenSuse 11.4
C++ - GCC 4.5.1
英特尔至强

Platform:
Linux - OpenSuse 11.4
C++ - GCC 4.5.1
Intel Xeon

推荐答案

由于段错误不是(直接)由软件引起的，而是由处理器检测到您试图访问无效内存(或访问无效内存方式 - 例如写入受写保护的内存，执行不应该执行的内存等)，它不是可捕获"的 try/catch，旨在捕获软件引发异常.它们都称为异常，但它们起源于系统软件/硬件的不同级别.

Since segfaults are not caused (directly) the the software, but rather by the processor detecting that you are trying to access invalid memory (or access memory in an invalid way - e.g writing to memory that is write-protected, executing memory that isn't supposed to be executed, etc), it is not "catchable" with try/catch, which is designed to catch software that throws an exception. They are both called exceptions, but they originate at different levels of the software/hardware of the system.

从技术上讲，您可以使用 SIGSEGV 的信号处理程序来捕获段错误.但是，正如 Ivaylo 解释的那样，如果您遇到段错误，通常不允许重试".SIGSEGV 的信号处理程序允许 longjmp 或 exit，但不应只返回.

Technically, you can catch segfaults with a signal handler for SIGSEGV. However, as Ivaylo explains, it's is not, typically, allowed to just "try again" if you get a segfault. The signal hander for SIGSEGV is allowed to longjmp or exit, but shouldn't just return.

在此处阅读有关信号的更多信息:http://www.alexonlinux.com/signal-handling-in-linux

Read more about signals here: http://www.alexonlinux.com/signal-handling-in-linux

可以毫无问题地重试典型的 C++ 异常(throw 的结果)(当然，同样的异常当然可能会再次抛出.

Typical C++ exceptions (result of throw) can be retried without problem (of course, the same exception may be thrown again, of course.

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