Michael Glassford schrieb:
Slawomir Lisznianski wrote:
Hello,
I find the catch(...) clause in the thread_proxy function (thread.cpp) causing more harm than good.
Does anyone have any comments on this? Support or objections?
I am somewhat surprised by the discussion. 1) How could a user function ever "wrap the code" at the thread_proxy level? There is nothing below on the stack?! Also see: m_thread = reinterpret_cast<void*>(_beginthreadex(0, 0, &thread_proxy, ¶m, 0, &m_id)); The only thing the catch all clause is doing is call the (somewhat superfluous) on_thread_exit() function on the windows platform, which currently only is used for TSS cleanup. Not sure about MPTASKS.) Removing the catch all at this point wouldn't change anything. In particular this would not stop unescaped throws from silently disappearing. An ending thread also does not normally stop the entire process doesn't it? I think the catch all is an artifact from the time before the below DLL_THREAD_DETACH was discovered. On windows the on_thread_exit is called by the operating system in either case: case DLL_THREAD_DETACH: { on_thread_exit(); break; } 2) To stop unescaped exceptions to slip through, one simple should wrap the user thread function with whatever clause is appropriate. And again I don't think it is too bad to forget the re-throw after a catch all at this stage. The on_thread_exit will simply be called later on. But wait, to be honest, there might be a difference: Depending on what the destructors of tls variables are doing, the C runtime library might be left with private leaking tls variables. Supported by the last observation the catch all at the thread proxy level simply is kind of a safeguard to omit this case. As I see it a user function always could catch all and not rethrow, thereby short-circuiting the call to on_thread_exit. So my recommendation is to leave things as they are, since they 1) wouldn't change much and 2) give an additional layer of tls leakage protection. Please correct me if I am on the wrong track. Regards, Roland