diff options
Diffstat (limited to 'SIGNALS')
| -rw-r--r-- | SIGNALS | 90 |
1 files changed, 77 insertions, 13 deletions
@@ -6,19 +6,28 @@ processes are documented here as well. === Master Process - * HUP - reload config file and gracefully restart all workers +* HUP - reload config file and gracefully restart all workers + If "preload_app" is false (the default), the application code + will be reloaded when workers are restarted as well. - * INT/TERM - quick shutdown, kills all workers immediately +* INT/TERM - quick shutdown, kills all workers immediately - * QUIT - graceful shutdown, waits for workers to finish their - current request before finishing. +* QUIT - graceful shutdown, waits for workers to finish their + current request before finishing. - * USR1 - reopen all logs owned by the master and all workers - See Unicorn::Util.reopen_logs for what is considered a log. +* USR1 - reopen all logs owned by the master and all workers + See Unicorn::Util.reopen_logs for what is considered a log. - * USR2 - reexecute the running binary. A separate QUIT - should be sent to the original process once the child is verified to - be up and running. +* USR2 - reexecute the running binary. A separate QUIT + should be sent to the original process once the child is verified to + be up and running. + +* WINCH - gracefully stops workers but keep the master running. + This will only work for daemonized processes. + +* TTIN - increment the number of worker processes by one + +* TTOU - decrement the number of worker processes by one === Worker Processes @@ -26,9 +35,64 @@ Sending signals directly to the worker processes should not normally be needed. If the master process is running, any exited worker will be automatically respawned. - * INT/TERM - quick shutdown, immediately exit +* INT/TERM - Quick shutdown, immediately exit. + Unless WINCH has been sent to the master (or the master is killed), + the master process will respawn a worker to replace this one. + +* QUIT - Gracefully exit after finishing the current request. + Unless WINCH has been sent to the master (or the master is killed), + the master process will respawn a worker to replace this one. + +* USR1 - Reopen all logs owned by the worker process. + See Unicorn::Util.reopen_logs for what is considered a log. + Log files are not reopened until it is done processing + the current request, so multiple log lines for one request + (as done by Rails) will not be split across multiple logs. + +=== Procedure to replace a running unicorn executable + +You may replace a running instance of unicorn with a new one without +losing any incoming connections. Doing so will reload all of your +application code, Unicorn config, Ruby executable, and all libraries. +The only things that will not change (due to OS limitations) are: + +1. The listener backlog size of already-bound sockets + +2. The path to the unicorn executable script. If you want to change to + a different installation of Ruby, you can modify the shebang + line to point to your alternative interpreter. + +The procedure is exactly like that of nginx: + +1. Send USR2 to the master process + +2. Check your process manager or pid files to see if a new master spawned + successfully. If you're using a pid file, the old process will have + ".oldbin" appended to its path. You should have two master instances + of unicorn running now, both of which will have workers servicing + requests. Your process tree should look something like this: + + unicorn master (old) + \_ unicorn worker[0] + \_ unicorn worker[1] + \_ unicorn worker[2] + \_ unicorn worker[3] + \_ unicorn master + \_ unicorn worker[0] + \_ unicorn worker[1] + \_ unicorn worker[2] + \_ unicorn worker[3] + +3. You can now send WINCH to the old master process so only the new workers + serve requests. If your unicorn process is bound to an interactive + terminal, you can skip this step. Step 5 will be more difficult but + you can also skip it if your process is not daemonized. + +4. You should now ensure that everything is running correctly with the + new workers as the old workers die off. - * QUIT - gracefully exit after finishing the current request +5. If everything seems ok, then send QUIT to the old master. You're done! - * USR1 - reopen all logs owned by the worker process - See Unicorn::Util.reopen_logs for what is considered a log. + If something is broken, then send HUP to the old master to reload + the config and restart its workers. Then send QUIT to the new master + process. |