"close race if an exit signal hits the worker before trap"

* Re: Strange quit behavior
  @ 2011-08-19 22:18  7%     ` Eric Wong
  0 siblings, 0 replies; 1+ results
From: Eric Wong @ 2011-08-19 22:18 UTC (permalink / raw)
  To: unicorn list

Eric Wong <normalperson@yhbt.net> wrote:
> Eric Wong <normalperson@yhbt.net> wrote:
> > If you SIGQUIT/SIGTERM before the app is loaded, the signal could
> > be ignored.  This behavior should probably change...
> 
> I pushed the following to git://bogomips.org/unicorn
> 
> From 406b8b0e2ed6e5be34d8ec3cd4b16048233c2856 Mon Sep 17 00:00:00 2001
> From: Eric Wong <normalperson@yhbt.net>
> Date: Tue, 2 Aug 2011 23:52:14 +0000
> Subject: [PATCH] trap death signals in the worker sooner
> 
> This helps close a race condition preventing shutdown if
> loading the application (preload_app=false) takes a long
> time and the user decides to kil workers instead.

The following completely eliminates the race condition:

>From 8de6ab371c1623669b86a5dfa8703c8fd539011f Mon Sep 17 00:00:00 2001
From: Eric Wong <normalperson@yhbt.net>
Date: Fri, 19 Aug 2011 22:13:04 +0000
Subject: [PATCH] close race if an exit signal hits the worker before trap

The signal handler from the master is still active and will
push the pending signal to SIG_QUEUE if a worker receives
a signal immediately after forking.
---
 lib/unicorn/http_server.rb |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/lib/unicorn/http_server.rb b/lib/unicorn/http_server.rb
index aa8212e..4f516c9 100644
--- a/lib/unicorn/http_server.rb
+++ b/lib/unicorn/http_server.rb
@@ -549,6 +549,7 @@ class Unicorn::HttpServer
   def init_worker_process(worker)
     # we'll re-trap :QUIT later for graceful shutdown iff we accept clients
     EXIT_SIGS.each { |sig| trap(sig) { exit!(0) } }
+    exit!(0) if (SIG_QUEUE & EXIT_SIGS)[0]
     WORKER_QUEUE_SIGS.each { |sig| trap(sig, nil) }
     trap(:CHLD, 'DEFAULT')
     SIG_QUEUE.clear
-- 
Eric Wong
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