FAQ: add entry for Rails autoflush_log

Thanks to Cedric Maion for bringing this up on the mailing list:
http://bogomips.org/unicorn-public/m/20140703144048.GA6674@cedric-maion.com

1 files changed, 9 insertions, 1 deletions

diff --git a/FAQ b/FAQ
index c84a8af..66f1a09 100644
--- a/FAQ
+++ b/FAQ
@@ -1,6 +1,14 @@
 = Frequently Asked Questions about Unicorn
 
-===  I've installed Rack 1.1.x, why can't Unicorn load Rails (2.3.5)?
+=== Why aren't my Rails log files rotated when I use SIGUSR1?
+
+The Rails autoflush_log option must remain disabled with multiprocess
+servers such as unicorn.  Buffering in userspace may cause lines to be
+partially written and lead to corruption in the presence of multiple
+processes.  With reasonable amounts of logging, the performance impact
+of autoflush_log should be negligible on Linux and other modern kernels.
+
+=== I've installed Rack 1.1.x, why can't Unicorn load Rails (2.3.5)?
 
 Rails 2.3.5 is not compatible with Rack 1.1.x.  Unicorn is compatible
 with both Rack 1.1.x and Rack 1.0.x, and RubyGems will load the latest