diff options
Diffstat (limited to 'unix/tclUnixThrd.c')
| -rw-r--r-- | unix/tclUnixThrd.c | 51 |
1 files changed, 49 insertions, 2 deletions
diff --git a/unix/tclUnixThrd.c b/unix/tclUnixThrd.c index f469341..ae81c5f 100644 --- a/unix/tclUnixThrd.c +++ b/unix/tclUnixThrd.c @@ -22,6 +22,19 @@ typedef struct ThreadSpecificData { static Tcl_ThreadDataKey dataKey; /* + * This is the number of milliseconds to wait between internal retries in + * the Tcl_MutexLock function. This value must be greater than zero and + * should be a suitable value for the given platform. + * + * TODO: This may need to be dynamically determined, based on the relative + * performance of the running process. + */ + +#ifndef TCL_MUTEX_LOCK_SLEEP_TIME +# define TCL_MUTEX_LOCK_SLEEP_TIME (25) +#endif + +/* * masterLock is used to serialize creation of mutexes, condition variables, * and thread local storage. This is the only place that can count on the * ability to statically initialize the mutex. @@ -45,6 +58,13 @@ static pthread_mutex_t allocLock = PTHREAD_MUTEX_INITIALIZER; static pthread_mutex_t *allocLockPtr = &allocLock; /* + * The mutexLock serializes Tcl_MutexLock. This is necessary to prevent + * races when finalizing a mutex that some other thread may want to lock. + */ + +static pthread_mutex_t mutexLock = PTHREAD_MUTEX_INITIALIZER; + +/* * These are for the critical sections inside this file. */ @@ -421,6 +441,8 @@ Tcl_MutexLock( { pthread_mutex_t *pmutexPtr; +retry: + if (*mutexPtr == NULL) { MASTER_LOCK; if (*mutexPtr == NULL) { @@ -435,8 +457,32 @@ Tcl_MutexLock( } MASTER_UNLOCK; } - pmutexPtr = *((pthread_mutex_t **)mutexPtr); - pthread_mutex_lock(pmutexPtr); + while (1) { + pthread_mutex_lock(&mutexLock); + pmutexPtr = *((pthread_mutex_t **)mutexPtr); + if (pmutexPtr == NULL) { + pthread_mutex_unlock(&mutexLock); + goto retry; + } + if (pthread_mutex_trylock(pmutexPtr) == 0) { + pthread_mutex_unlock(&mutexLock); + return; + } + pthread_mutex_unlock(&mutexLock); + /* + * BUGBUG: All core and Thread package tests pass when usleep() + * is used; however, the Thread package tests hang at + * various places when Tcl_Sleep() is used, typically + * while running test "thread-17.8", "thread-17.9", or + * "thread-17.11a". Really, what we want here is just + * to yield to other threads for a while. + */ +#ifdef HAVE_USLEEP + usleep(TCL_MUTEX_LOCK_SLEEP_TIME * 1000); +#else + Tcl_Sleep(TCL_MUTEX_LOCK_SLEEP_TIME); +#endif + } } /* @@ -727,6 +773,7 @@ TclpFreeAllocCache( */ TclFreeAllocCache(ptr); + pthread_setspecific(key, NULL); } else if (initialized) { /* |