kosaki	2011-06-15 01:31:23 +0900 (Wed, 15 Jun 2011)

  New Revision: 32091

  http://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=rev&revision=32091

  Log:
    * thread_pthread.c (gvl_yield): fix live lock issue on 1-2 cpus
      system. It's additional fix for r32021.
    * thread_pthread.c (gvl_init): add switch_wait_cond.
    * thread_pthread.h (typedef struct rb_global_vm_lock_struct): ditto.

  Modified files:
    trunk/ChangeLog
    trunk/thread_pthread.c
    trunk/thread_pthread.h

Index: ChangeLog
===================================================================
--- ChangeLog	(revision 32090)
+++ ChangeLog	(revision 32091)
@@ -1,3 +1,10 @@
+Wed Jun 15 01:27:53 2011  KOSAKI Motohiro  <kosaki.motohiro@g...>
+
+	* thread_pthread.c (gvl_yield): fix live lock issue on 1-2 cpus
+	  system. It's additional fix for r32021.
+	* thread_pthread.c (gvl_init): add switch_wait_cond.
+	* thread_pthread.h (typedef struct rb_global_vm_lock_struct): ditto.
+
 Tue Jun 14 23:16:22 2011  Tanaka Akira  <akr@f...>
 
 	* bootstraptest/runner.rb (show_progress): refine verbose mode.
Index: thread_pthread.c
===================================================================
--- thread_pthread.c	(revision 32090)
+++ thread_pthread.c	(revision 32091)
@@ -88,25 +88,35 @@
 {
     native_mutex_lock(&vm->gvl.lock);
 
+    __gvl_release(vm);
+
     /* An another thread is processing GVL yield. */
-    if (vm->gvl.need_yield) {
-	native_mutex_unlock(&vm->gvl.lock);
-	return;
+    if (UNLIKELY(vm->gvl.wait_yield)) {
+	while (vm->gvl.wait_yield)
+	    native_cond_wait(&vm->gvl.switch_wait_cond, &vm->gvl.lock);
+	goto acquire;
     }
 
+    vm->gvl.wait_yield = 1;
+
     if (vm->gvl.waiting > 0)
 	vm->gvl.need_yield = 1;
 
-    __gvl_release(vm);
     if (vm->gvl.need_yield) {
 	/* Wait until another thread task take GVL. */
-	native_cond_wait(&vm->gvl.switch_cond, &vm->gvl.lock);
-    } else {
+	while (vm->gvl.need_yield) {
+	    native_cond_wait(&vm->gvl.switch_cond, &vm->gvl.lock);
+	}
+    }
+    else {
 	native_mutex_unlock(&vm->gvl.lock);
 	sched_yield();
 	native_mutex_lock(&vm->gvl.lock);
     }
 
+    vm->gvl.wait_yield = 0;
+    native_cond_broadcast(&vm->gvl.switch_wait_cond);
+  acquire:
     __gvl_acquire(vm);
     native_mutex_unlock(&vm->gvl.lock);
 }
@@ -119,6 +129,7 @@
     native_mutex_initialize(&vm->gvl.lock);
     native_cond_initialize(&vm->gvl.cond, RB_CONDATTR_CLOCK_MONOTONIC);
     native_cond_initialize(&vm->gvl.switch_cond, RB_CONDATTR_CLOCK_MONOTONIC);
+    native_cond_initialize(&vm->gvl.switch_wait_cond, RB_CONDATTR_CLOCK_MONOTONIC);
     vm->gvl.acquired = 0;
     vm->gvl.waiting = 0;
     vm->gvl.need_yield = 0;
Index: thread_pthread.h
===================================================================
--- thread_pthread.h	(revision 32090)
+++ thread_pthread.h	(revision 32091)
@@ -45,7 +45,9 @@
 
     /* yield */
     rb_thread_cond_t switch_cond;
-    unsigned long need_yield;
+    rb_thread_cond_t switch_wait_cond;
+    int need_yield;
+    int wait_yield;
 } rb_global_vm_lock_t;
 
 #endif /* RUBY_THREAD_PTHREAD_H */

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