---------- Known bugs ---------- 1. Not strictly a bug, more of a gotcha. Under MS VC++ (only tested with version 6.0), a term_func set via the standard C++ set_terminate() function causes the application to abort. Notes from the MSVC++ manual: 1) A term_func() should call exit(), otherwise abort() will be called on return to the caller. A call to abort() raises SIGABRT and the default signal handler for all signals terminates the calling program with exit code 3. 2) A term_func() must not throw an exception. Therefore term_func() should not call pthread_exit(), which works by throwing an exception (pthreadVCE or pthreadVSE) or by calling longjmp (pthreadVC). Workaround: avoid using pthread_exit() in C++ applications. Exit threads by dropping through the end of the thread routine. 2. Cancellation problems in optimised code - Milan Gardian Workaround [rpj - 2 Feb 2002] ----------------------------- [Please note: this workaround did not solve a similar problem in snapshot-2004-11-03 or later, even though similar symptoms were seen. tests\semaphore4.c fails in that snapshot for the VCE version of the DLL. It suspected to be a compiler bug in VC6.0, and also seen in VC7.0.] The problem disappears when /Ob0 is used, i.e. /O2 /Ob0 works OK, but if you want to use inlining optimisation you can be much more specific about where it's switched off and on by using a pragma. So the inlining optimisation is interfering with the way that cleanup handlers are run. It appears to relate to auto-inlining of class methods since this is the only auto inlining that is performed at /O1 optimisation (functions with the "inline" qualifier are also inlined, but the problem doesn't appear to involve any such functions in the library or testsuite). In order to confirm the inlining culprit, the following use of pragmas eliminate the problem but I don't know how to make it transparent, putting it in, say, pthread.h where pthread_cleanup_push defined as a macro. #pragma inline_depth(0) pthread_cleanup_push(handlerFunc, (void *) &arg); /* ... */ pthread_cleanup_pop(0); #pragma inline_depth() Note the empty () pragma value after the pop macro. This resets depth to the default. Or you can specify a non-zero depth here. The pragma is also needed (and now used) within the library itself wherever cleanup handlers are used (condvar.c and rwlock.c). Use of these pragmas allows compiler optimisations /O1 and /O2 to be used for either or both the library and applications. Experimenting further, I found that wrapping the actual cleanup handler function with #pragma auto_inline(off|on) does NOT work. MSVC6.0 doesn't appear to support the C99 standard's _Pragma directive, however, later versions may. This form is embeddable inside #define macros, which would be ideal because it would mean that it could be added to the push/pop macro definitions in pthread.h and hidden from the application programmer. [/rpj] Original problem description ---------------------------- The cancellation (actually, cleanup-after-cancel) tests fail when using VC (professional) optimisation switches (/O1 or /O2) in pthreads library. I have not investigated which concrete optimisation technique causes this problem (/Og, /Oi, /Ot, /Oy, /Ob1, /Gs, /Gf, /Gy, etc.), but here is a summary of builds and corresponding failures: * pthreads VSE (optimised tests): OK * pthreads VCE (optimised tests): Failed "cleanup1" test (runtime) * pthreads VSE (DLL in CRT, optimised tests): OK * pthreads VCE (DLL in CRT, optimised tests): Failed "cleanup1" test (runtime) Please note that while in VSE version of the pthreads library the optimisation does not really have any impact on the tests (they pass OK), in VCE version addition of optimisation (/O2 in this case) causes the tests to fail uniformly - either in "cleanup0" or "cleanup1" test cases. Please note that all the tests above use default pthreads DLL (no optimisations, linked with either static or DLL CRT, based on test type). Therefore the problem lies not within the pthreads DLL but within the compiled client code (the application using pthreads -> involvement of "pthread.h"). I think the message of this section is that usage of VCE version of pthreads in applications relying on cancellation/cleanup AND using optimisations for creation of production code is highly unreliable for the current version of the pthreads library.