MINOR: threads: add a "stuck" flag to the thread_info struct
This flag is constantly cleared by the scheduler and will be set by the
watchdog timer to detect stuck threads. It is also set by the "show
threads" command so that it is easy to spot if the situation has evolved
between two subsequent calls : if the first "show threads" shows no stuck
thread and the second one shows such a stuck thread, it indicates that
this thread didn't manage to make any forward progress since the previous
call, which is extremely suspicious.
diff --git a/src/debug.c b/src/debug.c
index e47b85c..b34df72 100644
--- a/src/debug.c
+++ b/src/debug.c
@@ -33,18 +33,20 @@
* optionally extra info for the current thread. The dump will be appended to
* the buffer, so the caller is responsible for preliminary initializing it.
* The calling thread ID needs to be passed in <calling_tid> to display a star
- * in front of the calling thread's line (usually it's tid).
+ * in front of the calling thread's line (usually it's tid). Any stuck thread
+ * is also prefixed with a '>'.
*/
void ha_thread_dump(struct buffer *buf, int thr, int calling_tid)
{
unsigned long thr_bit = 1UL << thr;
unsigned long long p = thread_info[thr].prev_cpu_time;
unsigned long long n = now_cpu_time_thread(&thread_info[thr]);
+ int stuck = !!(thread_info[thr].flags & TI_FL_STUCK);
chunk_appendf(buf,
- "%c Thread %-2u: act=%d glob=%d wq=%d rq=%d tl=%d tlsz=%d rqsz=%d\n"
- " fdcache=%d prof=%d",
- (thr == calling_tid) ? '*' : ' ', thr + 1,
+ "%c%cThread %-2u: act=%d glob=%d wq=%d rq=%d tl=%d tlsz=%d rqsz=%d\n"
+ " stuck=%d fdcache=%d prof=%d",
+ (thr == calling_tid) ? '*' : ' ', stuck ? '>' : ' ', thr + 1,
!!(active_tasks_mask & thr_bit),
!!(global_tasks_mask & thr_bit),
!eb_is_empty(&task_per_thread[thr].timers),
@@ -52,6 +54,7 @@
!LIST_ISEMPTY(&task_per_thread[thr].task_list),
task_per_thread[thr].task_list_size,
task_per_thread[thr].rqueue_size,
+ stuck,
!!(fd_cache_mask & thr_bit),
!!(task_profiling_mask & thr_bit));
@@ -467,6 +470,12 @@
else
ha_thread_relax();
}
+
+ /* mark the current thread as stuck to detect it upon next invocation
+ * if it didn't move.
+ */
+ if (!((threads_harmless_mask|sleeping_thread_mask) & tid_bit))
+ ti->flags |= TI_FL_STUCK;
}
static int init_debug_per_thread()