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Diffstat (limited to 'FAQ')
| -rw-r--r-- | FAQ | 68 |
1 files changed, 68 insertions, 0 deletions
@@ -14,6 +14,10 @@ Q 3 How do I use pthread.dll for Win32 (Visual C++ 5.0) Q 4 Cancelation doesn't work for me, why? +Q 5 Thread won't block after two calls to mutex_lock + +Q 6 How do I generate libpthread.a for use with Mingw32? + ============================================================================= Q 1 Should I use Cygwin or Mingw32 as a development environment? @@ -253,3 +257,67 @@ a thread is going to block on a Win32 handle. These are: Regards. Ross +------------------------------------------------------------------------------ + +Q 5 Thread won't block after two calls to mutex_lock +--- + +A 5 +--- + +> i was testing this pthread for win32 in my prog. +> when i checked if it was blocking mutex_lock calls, i was surprised when it +> didnt lock +> +> pthread_mutex_t DBlock; +> +> pthread_mutex_init( &DBlock, NULL ); +> pthread_mutex_lock( &DBlock ); +> pthread_mutex_lock( &DBlock ); +> +> ^^ these two calls didnt block + +POSIX leaves the result "undefined" for a thread that tries +to recursively lock the same mutex (one that it owns already). +That means the actual semantics are left up to the +implementation, but should not be relied upon for code that +will be ported to different POSIX threads implementations. + +In the pthreads-win32 implementation a thread won't deadlock +itself by relocking the mutex. Subsequent calls to +pthread_mutex_lock() as in your example above increment +the lock count but the thread continues on. Consequently, +the thread must ensure that it unlocks the mutex once for +each lock operation. That is, pthreads-win32 mutexes are +always recursive. + +You may want to look at the other synchronisation devices +available in the library, such as condition variables or +read-write locks. + +Ross + +------------------------------------------------------------------------------ + +Q 6 How do I generate libpthread.a for use with Mingw32? +--- + +A 6 +--- + +> I'm lacking the libpthread.a that +> used to come with the pre-compiled package. The last time this +> library appeared was in 1999-08-12. Without this library I cannot +> use the pre-compiled dll. + +You can create libpthread.a from the .def file, should work along these +lines: + +$(DLLTOOL) --as $(AS) -k --dllname libpthread.dll --output-lib +libpthread.a --def $(srcdir)/libpthread.def + +Where DLLTOOL is i686-pc-cygwin-dlltool +and AS i686-pc-cygwin-as. + +Thomas Sailer <sailer@ife.ee.ethz.ch> + |