Google C++ coding style, no exceptions rule. What about multithreading?

Question

Google C++ coding style recommends against C++ exceptions, and we don't use them too. For most of the STL library containers one can just ignore the exceptions, because normally they indicate critical errors and are difficult to handle anyway, so crashing is acceptable.

However there is a problem with multi-threading (std::thread), for example entering a non-recursive mutex twice throws an exception. This situation is not critical and could be handled by waiting.

My question is: anyone knows what is Google using as a threading library? Is there any C++ cross-platform threading library that doesn't use exceptions?

Thank you

Answer 1

It should be noted that Google's style guide does not not preclude the handing of exceptions rather the throwing of exceptions. I.e. deal with the problem, but don't make it any worse by throwing more exceptions.

In the case of re-entering a non-recursive mutex: that is clearly a programmer error rather than some unexpected bolt from the blue. The exception should be allowed to propagate up to the calling code so that it can be seen and dealt with as a bug. It should be noted that the Google Test framework does not rely on exceptions, but it can certainly catch and report them.

While Google's style guide takes an extreme position, there is no doubt that exceptions can highly problematic when writing reusable libraries. For example, we found developing with WinCE 6.0 that exceptions got sliced on re-throwing and on ARM platforms couldn't be reliably thrown across DLL boundaries. In addition, catching an exception could take several milliseconds, so they definitely shouldn't be used for non-exceptional circumstances (i.e. 'expected' errors) where real-time performance is required. The clue's in the name really.

Answer 2

The practices in Google's style guide dates back to the early nineties of the previous century, when threads were rather exotic beasts. As such, it doesn't make sense to wonder how that style and threads would mix. If you use "modern" (21st century) techniques like threads, you don't use Google's style guide and vice versa.