From cba4e1c0a3423ed07ef5c79f6e29360996f32fd7 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Sun, 25 Sep 2011 02:38:03 -0400 Subject: new futex-requeue-based pthread_cond_broadcast implementation this avoids the "stampede effect" where pthread_cond_broadcast would result in all waiters waking up simultaneously, only to immediately contend for the mutex and go back to sleep. --- src/thread/pthread_cond_init.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'src/thread/pthread_cond_init.c') diff --git a/src/thread/pthread_cond_init.c b/src/thread/pthread_cond_init.c index dc4fb981..03aff768 100644 --- a/src/thread/pthread_cond_init.c +++ b/src/thread/pthread_cond_init.c @@ -3,6 +3,9 @@ int pthread_cond_init(pthread_cond_t *c, const pthread_condattr_t *a) { memset(c, 0, sizeof *c); - if (a) c->_c_clock = *a & 0x7fffffff; + if (a) { + c->_c_clock = *a & 0x7fffffff; + if (*a>>31) c->_c_mutex = (void *)-1; + } return 0; } -- cgit v1.2.1