Ruby

とりあえず以下のような感じで作ってみました。
やっぱりバックトレースも欲しいかな

% ./miniruby -ve'Thread.current.name="MainThread!";z=Thread.new{Thread.stop};a,b=Thread.new{1until b;b.join},Thread.new{1until a;a.join};a.name="aaaaa";b.name="bbbbb";z.name="zzzz";a.join' `miniruby' is up to date. ruby 2.4.0dev (2016-06-01 trunk 55248) [x86_64-freebsd10.3] -e:1:in `join': No live threads left. Deadlock? (fatal) 4 threads, 4 sleeps current:0x00000802c1b200 main thread:0x00000802c17300 * #<Thread:0x00000802d8ce58@MainThread! sleep_forever> rb_thread_t:0x00000802c17300 native:0x00000802c06400 int:1 * #<Thread:0x00000802d7f780@zzzz@-e:1 sleep_forever> rb_thread_t:0x00000802c1ac00 native:0x00000802c07800 int:0 * #<Thread:0x00000802d7f690@aaaaa@-e:1 sleep_forever> rb_thread_t:0x00000802c1af00 native:0x00000802c07c00 int:0 depended by: tb_thread_id:0x00000802c1b200 depended by: tb_thread_id:0x00000802c17300 * #<Thread:0x00000802d7f5a0@bbbbb@-e:1 sleep_forever> rb_thread_t:0x00000802c1b200 native:0x00000802c08000 int:0 depended by: tb_thread_id:0x00000802c1af00 from -e:1:in `<main>' 

diff --git a/thread.c b/thread.c index d17b663..359dada 100644 --- a/thread.c +++ b/thread.c @@ -2618,7 +2618,7 @@ 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: @@ -2626,8 +2626,9 @@ 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"; @@ -2687,7 +2688,7 @@ rb_thread_status(VALUE thread)	}	return Qfalse; } - return rb_str_new2(thread_status_name(th)); + return rb_str_new2(thread_status_name(th, FALSE));  } @@ -2833,7 +2834,7 @@ rb_thread_inspect(VALUE thread) VALUE str; GetThreadPtr(thread, th); - status = thread_status_name(th); + status = thread_status_name(th, FALSE);  str = rb_sprintf("#<%"PRIsVALUE":%p", cname, (void *)thread); if (!NIL_P(th->name)) {	rb_str_catf(str, "@%"PRIsVALUE, th->name); @@ -4728,26 +4729,36 @@ ruby_native_thread_p(void) } 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; - 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, " rb_thread_t:%p %s %u waiting:%p cond_waiting:%d", th, thread_status_name(th, TRUE), th->interrupt_flag, mth, waiting); +	} +	else { + rb_str_catf(msg, " rb_thread_t:%p %s %u\n", th, thread_status_name(th, TRUE), th->interrupt_flag); +	} +	{ + rb_thread_list_t *list = th->join_list; + while (list) { +	rb_str_catf(msg, " depended by: %p\n", list->th); +	list = list->next; + } 	} -	else - puts("");  } -#endif  } static void @@ -4782,7 +4793,7 @@ 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); } 

バックトレースも欲しいらしいので

% ./miniruby -ve'Thread.current.name="MainThread!";z=Thread.new{Thread.stop};a,b=Thread.new{1until b;b.join},Thread.new{1until a;a.join};a.name="aaaaa";b.name="bbbbb";z.name="zzzz";a.join' --- thread.o --- compiling ../../ruby/thread.c --- miniruby --- linking miniruby ruby 2.4.0dev (2016-06-01 trunk 55248) [x86_64-freebsd10.3] -e:1:in `join': No live threads left. Deadlock? (fatal) 4 threads, 4 sleeps current:0x00000802c1b200 main thread:0x00000802c17300 * #<Thread:0x00000802d8ce58@MainThread! sleep_forever> rb_thread_t:0x00000802c17300 native:0x00000802c06400 int:1 -e:1:in `join' -e:1:in `<main>' * #<Thread:0x00000802d7f780@zzzz@-e:1 sleep_forever> rb_thread_t:0x00000802c1ac00 native:0x00000802c07800 int:0 -e:1:in `stop' -e:1:in `block in <main>' * #<Thread:0x00000802d7f690@aaaaa@-e:1 sleep_forever> rb_thread_t:0x00000802c1af00 native:0x00000802c07c00 int:0 depended by: tb_thread_id:0x00000802c1b200 depended by: tb_thread_id:0x00000802c17300 -e:1:in `join' -e:1:in `block in <main>' * #<Thread:0x00000802d7f5a0@bbbbb@-e:1 sleep_forever> rb_thread_t:0x00000802c1b200 native:0x00000802c08000 int:0 depended by: tb_thread_id:0x00000802c1af00 -e:1:in `join' -e:1:in `block in <main>' from -e:1:in `<main>' 

diff --git a/thread.c b/thread.c index d17b663..84f76d1 100644 --- a/thread.c +++ b/thread.c @@ -2618,7 +2618,7 @@ 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: @@ -2626,8 +2626,9 @@ 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"; @@ -2687,7 +2688,7 @@ rb_thread_status(VALUE thread)	}	return Qfalse; } - return rb_str_new2(thread_status_name(th)); + return rb_str_new2(thread_status_name(th, FALSE));  } @@ -2833,7 +2834,7 @@ 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); @@ -4727,27 +4728,46 @@ 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 @@ -4782,7 +4802,7 @@ 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); } 

デッドロック関連のデバッグであれば A -> B の順にロックを取ろうとしているスレッドと B -> A の順に
ロックを取ろうとしているスレッドが両方いる、という事実が重要だと思うので、バックトレースは極めて重要だと考えます。