diff options
Diffstat (limited to 'TUNING')
| -rw-r--r-- | TUNING | 40 |
1 files changed, 31 insertions, 9 deletions
@@ -1,12 +1,34 @@ -= Tuning Unicorn += Tuning \Unicorn -Unicorn performance is generally as good as a (mostly) Ruby web server +\Unicorn performance is generally as good as a (mostly) Ruby web server can provide. Most often the performance bottleneck is in the web application running on Unicorn rather than Unicorn itself. -== Unicorn Configuration +== \Unicorn Configuration See Unicorn::Configurator for details on the config file format. ++worker_processes+ is the most-commonly needed tuning parameter. + +=== Unicorn::Configurator#worker_processes + +* worker_processes should be scaled to the number of processes your + backend system(s) can support. DO NOT scale it to the number of + external network clients your application expects to be serving. + \Unicorn is NOT for serving slow clients, that is the job of nginx. + +* worker_processes should be *at* *least* the number of CPU cores on + a dedicated server. If your application has occasionally slow + responses that are /not/ CPU-intensive, you may increase this to + workaround those inefficiencies. + +* worker_processes may be increased for Unicorn::OobGC users to provide + more consistent response times. + +* Never, ever, increase worker_processes to the point where the system + runs out of physical memory and hits swap. Production servers should + never see heavy swap activity. + +=== Unicorn::Configurator#listen Options * Setting a very low value for the :backlog parameter in "listen" directives can allow failover to happen more quickly if your @@ -30,6 +52,11 @@ See Unicorn::Configurator for details on the config file format. and may also thrash CPU caches, cancelling out performance gains one would normally expect. +* UNIX domain sockets are slighly faster than TCP sockets, but only + work if nginx is on the same machine. + +== Other \Unicorn settings + * Setting "preload_app true" can allow copy-on-write-friendly GC to be used to save memory. It will probably not work out of the box with applications that open sockets or perform random I/O on files. @@ -40,12 +67,7 @@ See Unicorn::Configurator for details on the config file format. * On POSIX-compliant filesystems, it is safe for multiple threads or processes to append to one log file as long as all the processes are have them unbuffered (File#sync = true) or they are - record(line)-buffered in userspace. - -* worker_processes should be scaled to the number of processes your - backend system(s) can support. DO NOT scale it to the number of - external network clients your application expects to be serving. - Unicorn is NOT for serving slow clients, that is the job of nginx. + record(line)-buffered in userspace before any writes. == Kernel Parameters (Linux sysctl) |