Merge pull request #115 from ruby/drop-hourly-apache-restart

Stop the hourly apache2 restart and raise MaxRequestWorkers

Author: hsbt

recipes/apache2.rb

@@ -33,6 +33,17 @@
   to '../conf-available/cgit.conf'
 end
 
+remote_file '/etc/apache2/conf-available/mpm-tuning.conf' do
+  mode  '644'
+  owner 'root'
+  notifies :restart, 'service[apache2]'
+end
+
+link '/etc/apache2/conf-enabled/mpm-tuning.conf' do
+  to '../conf-available/mpm-tuning.conf'
+  notifies :restart, 'service[apache2]'
+end
+
 %w[git svn].each do |subdomain|
   remote_file "/etc/apache2/sites-available/#{subdomain}.ruby-lang.org.conf" do
     mode  '644'
@@ -76,3 +87,13 @@
     end
   end
 end
+
+# root's crontab carried "20 * * * * systemctl restart apache2" from before
+# Anubis, outside this repository. It fixed nothing: children settle at 25 MB
+# and never leak. It caused harm instead. 57 of the 91 AH00484 (MaxRequestWorkers
+# exhausted) events in the last two weeks landed within eight minutes of it,
+# because the 63,000 requests an hour arriving at the front door all reconnect
+# at once against StartServers 2.
+file '/var/spool/cron/crontabs/root' do
+  action :delete
+end

recipes/files/etc/apache2/conf-available/mpm-tuning.conf

@@ -0,0 +1,12 @@
+# Overrides what mods-available/mpm_event.conf sets. That file is a dpkg
+# conffile, so it is left alone and this one wins by being included later.
+#
+# Browsing costs two workers rather than one: the front vhost proxies to Anubis
+# and Anubis proxies back into this same apache on port 3001. Debian's default
+# of 150 therefore caps concurrent browsing at 75, and AH00484 fires on bursts
+# even though steady state is 35 to 55 busy workers. 16 children of 25 threads
+# is the event MPM's own ServerLimit, and costs about 400 MB out of 7 GB.
+<IfModule mpm_event_module>
+	ServerLimit			 16
+	MaxRequestWorkers	400
+</IfModule>