* thread.c (debug_deadlock_check): show thread lock dependency and

backtrace [Feature #8214] [ruby-dev:47217]

* thread.c (thread_status_name): show "sleep_forever" instead of
  "sleep" if called from inspect.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@55397 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,11 @@
+Mon Jun 13 21:09:40 2016  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* thread.c (debug_deadlock_check): show thread lock dependency and
+	  backtrace [Feature #8214] [ruby-dev:47217]
+
+	* thread.c (thread_status_name): show "sleep_forever" instead of
+	  "sleep" if called from inspect.
+
 Mon Jun 13 20:50:07 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* parse.y (reg_named_capture_assign_iter): remove named capture

NEWS

@@ -167,3 +167,5 @@ with all sufficient information, see the ChangeLog file or Redmine
   be <= 0x100, and Array#max and min must not be redefined.  It will work
   in most casual and real-life use case where it is written with intent
   to `Math.max(x, y)`.
+
+* Thread deadlock detection now shows their backtrace and dependency. [Feature #8214]

thread.c

@@ -2737,7 +2737,7 @@ rb_thread_group(VALUE thread)
 }
 
 static const char *
-thread_status_name(rb_thread_t *th)
+thread_status_name(rb_thread_t *th, int detail)
 {
     switch (th->status) {
       case THREAD_RUNNABLE:
@@ -2745,8 +2745,9 @@ thread_status_name(rb_thread_t *th)
 	    return "aborting";
 	else
 	    return "run";
-      case THREAD_STOPPED:
       case THREAD_STOPPED_FOREVER:
+	if (detail) return "sleep_forever";
+      case THREAD_STOPPED:
 	return "sleep";
       case THREAD_KILLED:
 	return "dead";
@@ -2806,7 +2807,7 @@ rb_thread_status(VALUE thread)
 	}
 	return Qfalse;
     }
-    return rb_str_new2(thread_status_name(th));
+    return rb_str_new2(thread_status_name(th, FALSE));
 }
 
 
@@ -2952,7 +2953,7 @@ rb_thread_inspect(VALUE thread)
     VALUE str;
 
     GetThreadPtr(thread, th);
-    status = thread_status_name(th);
+    status = thread_status_name(th, TRUE);
     str = rb_sprintf("#<%"PRIsVALUE":%p", cname, (void *)thread);
     if (!NIL_P(th->name)) {
 	rb_str_catf(str, "@%"PRIsVALUE, th->name);
@@ -4850,27 +4851,46 @@ ruby_native_thread_p(void)
     return th != 0;
 }
 
+VALUE rb_vm_backtrace_str_ary(rb_thread_t *th, long lev, long n);
 static void
-debug_deadlock_check(rb_vm_t *vm)
+debug_deadlock_check(rb_vm_t *vm, VALUE msg)
 {
-#ifdef DEBUG_DEADLOCK_CHECK
     rb_thread_t *th = 0;
+    VALUE sep = rb_str_new_cstr("\n   ");
 
-    printf("%d %d %p %p\n", vm_living_thread_num(vm), vm->sleeper, GET_THREAD(), vm->main_thread);
+    rb_str_catf(msg, "\n%d threads, %d sleeps current:%p main thread:%p\n",
+	    vm_living_thread_num(vm), vm->sleeper, GET_THREAD(), vm->main_thread);
     list_for_each(&vm->living_threads, th, vmlt_node) {
-	printf("th:%p %d %d", th, th->status, th->interrupt_flag);
 	if (th->locking_mutex) {
 	    rb_mutex_t *mutex;
+	    struct rb_thread_struct volatile *mth;
+	    int waiting;
 	    GetMutexPtr(th->locking_mutex, mutex);
 
 	    native_mutex_lock(&mutex->lock);
-	    printf(" %p %d\n", mutex->th, mutex->cond_waiting);
+	    mth = mutex->th;
+	    waiting = mutex->cond_waiting;
 	    native_mutex_unlock(&mutex->lock);
+	    rb_str_catf(msg, "* %+"PRIsVALUE"\n   rb_thread_t:%p native:%p int:%u mutex:%p cond:%d\n",
+		    th->self, th, th->thread_id,
+		    th->interrupt_flag, mth, waiting);
 	}
-	else
-	    puts("");
+	else {
+	    rb_str_catf(msg, "* %+"PRIsVALUE"\n   rb_thread_t:%p native:%p int:%u\n",
+		    th->self, th, th->thread_id,
+		    th->interrupt_flag);
+	}
+	{
+	    rb_thread_list_t *list = th->join_list;
+	    while (list) {
+		rb_str_catf(msg, "    depended by: tb_thread_id:%p\n", list->th);
+		list = list->next;
+	    }
+	}
+	rb_str_catf(msg, "   ");
+	rb_str_concat(msg, rb_ary_join(rb_vm_backtrace_str_ary(th, 0, 0), sep));
+	rb_str_catf(msg, "\n");
     }
-#endif
 }
 
 static void
@@ -4905,7 +4925,7 @@ rb_check_deadlock(rb_vm_t *vm)
 	VALUE argv[2];
 	argv[0] = rb_eFatal;
 	argv[1] = rb_str_new2("No live threads left. Deadlock?");
-	debug_deadlock_check(vm);
+	debug_deadlock_check(vm, argv[1]);
 	vm->sleeper--;
 	rb_threadptr_raise(vm->main_thread, 2, argv);
     }