[Boost-users] Boost.Thread : catching all exceptions

From: Adrian Mawbey (adrian.mawbey_at_[hidden])
Date: 2005-06-13 18:23:44

Hi folks.

Apologies if this has been discussed frequently before.

I'm puzzled as to why the boost.thread thread_proxy function catches all 
exceptions and then quietly ends the thread.

For example:-

class MyThreadFunctor
{
public:
    void operator()() const
    {
        // Do some processing...
        throw very_bad_exception();
        // ...never get to do some processing.
    }
};

int main(int argc, char * argv[])
{
    MyThreadFunctor my_functor;
    boost::thread my_thread(my_functor);
    // Do lots of processing and then join to my_thread.
    // ...
}

In boost 1.32, the exception that is thrown in the created thread is caught in 
the library's thread_proxy function and then the thread exits quietly.

Is there a compelling reason for this behaviour?

>From my point of view, it seems more flexible to not catch exceptions in 
the thread_proxy function. If I wanted to, I could still get the current 
behaviour by putting a try/catch-all block in the operator() function.

I would have expected the normal C++ uncaught exception actions (i.e. calling 
terminate()) to occur if an exception is thrown out of the user provided 
thread code.

I noticed this when (oh horror!) an error in my code threw an exception out of 
operator(). I could have identified where the problem was from the core file 
or Dr Watson log that would have been created if the exception had not been 
caught by thread_proxy().

Am I missing something obvious here?

Thanks,
Adrian.