Unicorn_rails ignores USR2 signal

Eric Wong normalperson at yhbt.net
Sat Mar 10 01:30:51 UTC 2012


"Yeung, Jeffrey" <Jeffrey.Yeung at polycom.com> wrote:
> I have it configured for 4 workers.  I just turned it down to 1 worker
> and tested both TTIN and TTOU.  They both work, creating and killing
> workers, respectively.  The following is the strace capture from an
> TTOU signal, followed by a USR2 signal.  Yes, that is the only output
> from the USR2 signal.  Behavior doesn't change if the master is
> freshly started, or has been running for a while.  One other thing I
> did not mention earlier is that the <pid>.oldbin file never gets
> created on the USR2 signal, but that's probably obvious already.

I also asked for sending another signal after USR2, can you try that?

However, there's another possibility I hadn't considered, what if you
disable preload_app?  Your app or some libs it uses may be intercepting
USR2 for something it does.

Maybe this patch can work, but this may also silently break your
application/lib, too...

diff --git a/lib/unicorn/http_server.rb b/lib/unicorn/http_server.rb
index 7d2c623..1b9d693 100644
--- a/lib/unicorn/http_server.rb
+++ b/lib/unicorn/http_server.rb
@@ -128,8 +128,7 @@ class Unicorn::HttpServer
     # setup signal handlers before writing pid file in case people get
     # trigger happy and send signals as soon as the pid file exists.
     # Note that signals don't actually get handled until the #join method
-    QUEUE_SIGS.each { |sig| trap(sig) { SIG_QUEUE << sig; awaken_master } }
-    trap(:CHLD) { awaken_master }
+    master_siginit
     self.pid = config[:pid]
 
     self.master_pid = $$
@@ -689,6 +688,9 @@ class Unicorn::HttpServer
         Gem.refresh
       end
       self.app = app.call
+
+      # override signal handlers the app may have set
+      master_siginit if preload_app
     end
   end
 
@@ -736,4 +738,9 @@ class Unicorn::HttpServer
     config_listeners.each { |addr| listen(addr) }
     raise ArgumentError, "no listeners" if LISTENERS.empty?
   end
+
+  def master_siginit
+    QUEUE_SIGS.each { |sig| trap(sig) { SIG_QUEUE << sig; awaken_master } }
+    trap(:CHLD) { awaken_master }
+  end
 end


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