Re: [PATCH] Add worker_exec configuration option V2

[Jeremy Evans <code@jeremyevans.net>]

On 03/11 07:18, Eric Wong wrote:
> Jeremy Evans <code@jeremyevans.net> wrote:
> > On 03/10 09:19, Eric Wong wrote:
> > > Jeremy Evans <code@jeremyevans.net> wrote:
> > > > -      if pid = fork
> > > > -        @workers[pid] = worker
> > > > -        worker.atfork_parent
> > > > +
> > > > +      pid = if @worker_exec
> > > > +        worker_spawn(worker)
> > > >        else
> > > > -        after_fork_internal
> > > > -        worker_loop(worker)
> > > > -        exit
> > > > +        fork do
> > > > +          after_fork_internal
> > > > +          worker_loop(worker)
> > > > +          exit
> > > > +        end
> > > 
> > > I prefer to avoid the block with fork.  The block deepens the
> > > stack for the running app, so it can affect GC efficiency.
> > > 
> > > Can be fixed in a separate patch...
> > 
> > That makes sense.  If you would like me to send a separate patch to fix
> > it, I can do that.
> 
> Yes, please.
> 
> Not sure if we should automate the stack depth test...
> I resisted it in the past since it might be too fragile
> w.r.t changes to Ruby (even using "unicorn" via the
> RubyGems-generated wrapper deepens it by 2).

Here's a patch to fix the stack depth issue:

From aa4914846a0870e5b01530a47d6dbfe09aeb39ce Mon Sep 17 00:00:00 2001
From: Jeremy Evans <code@jeremyevans.net>
Date: Mon, 13 Mar 2017 08:28:54 -0700
Subject: [PATCH] Don't pass a block for fork when forking workers

This reduces the stack depth, making GC more efficient.
---
 lib/unicorn/http_server.rb | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/lib/unicorn/http_server.rb b/lib/unicorn/http_server.rb
index a5bd2c4..023df10 100644
--- a/lib/unicorn/http_server.rb
+++ b/lib/unicorn/http_server.rb
@@ -541,14 +541,12 @@ def spawn_missing_workers
       worker = Unicorn::Worker.new(worker_nr)
       before_fork.call(self, worker)
 
-      pid = if @worker_exec
-        worker_spawn(worker)
-      else
-        fork do
-          after_fork_internal
-          worker_loop(worker)
-          exit
-        end
+      pid = @worker_exec ?  worker_spawn(worker) : fork
+      
+      unless pid
+        after_fork_internal
+        worker_loop(worker)
+        exit
       end
 
       @workers[pid] = worker
-- 
2.11.0