MEDIUM: unblock signals on startup.
A problem was reported recently by some users of programs compiled
with Go 1.5 which by default blocks all signals before executing
processes, resulting in haproxy not receiving SIGUSR1 or even SIGTERM,
causing lots of zombie processes.
This problem was apparently observed by users of consul and kubernetes
(at least).
This patch is a workaround for this issue. It consists in unblocking
all signals on startup. Since they're normally not blocked in a regular
shell, it ensures haproxy always starts under the same conditions.
Quite useful information reported by both Matti Savolainen and REN
Xiaolei actually helped find the root cause of this problem and this
workaround. Thanks to them for this.
This patch must be backported to 1.6 and 1.5 where the problem is
observed.
(cherry picked from commit d50b4ac0d4acb00e0d2386198191ac329e8dbb77)
(cherry picked from commit f04d87284a0ecbb9af9182d3ca576a9e27fefced)
diff --git a/src/signal.c b/src/signal.c
index e9301ed..7b72622 100644
--- a/src/signal.c
+++ b/src/signal.c
@@ -105,6 +105,14 @@
signal_queue_len = 0;
memset(signal_queue, 0, sizeof(signal_queue));
memset(signal_state, 0, sizeof(signal_state));
+
+ /* Ensure signals are not blocked. Some shells or service managers may
+ * accidently block all of our signals unfortunately, causing lots of
+ * zombie processes to remain in the background during reloads.
+ */
+ sigemptyset(&blocked_sig);
+ sigprocmask(SIG_SETMASK, &blocked_sig, NULL);
+
sigfillset(&blocked_sig);
sigdelset(&blocked_sig, SIGPROF);
for (sig = 0; sig < MAX_SIGNAL; sig++)