Gunicorn signal Processing (SIGHUP,SIGUSR2)

In this article, the master process is referred to the signal processing function, where two of the signals are more interesting. SIGHUP: Used for hot update (RELOAD) applications SIGUSR2: For online upgrade (upgrade on the fly) Gunicorn below for a detailed look: SIGHUP:

Reload The configuration, start the new worker processes with a new configuration and gracefully shutdown  Older workers.

The sigup corresponding signal processing function is arbiter.reload. The simplified core code is as follows:

1     defReload (self):2Old_address =self.cfg.address3  4         #Reload conf, reload configuration5 self.app.reload ()6 Self.setup (Self.app)7  8         #Reopen log Files9 self.log.reopen_files ()Ten   One         #Do we need to change listener?, handling the situation of monitoring port changes A         ifOld_address! =self.cfg.address: -             #Close all listeners -[L.close () forLinchSelf . LISTENERS] the             #Init new Listeners -Self. LISTENERS =create_sockets (self.cfg, Self.log) -Listeners_str =",". join ([STR (L) forLinchSelf . LISTENERS]) -Self.log.info ("Listening at:%s", Listeners_str) +   -         #spawn new workers, starting a fresh worker (quantity and type from the new configuration) +          forIinchRange (self.cfg.workers): A Self.spawn_worker () at   -         #manage workers, this will kill the original worker. -Self.manage_workers ()

Mentioned in the above reference, will " Elegance(graceful) to kill the old worker process. The implementation is also very simple, arbiter for each fork out of the worker process to set a self-increasing "worker_age", the smaller the worker, this property indicates that the older worker. In Manage_workers, if the number of worker processes that have been started is greater than the number in the configuration, the older worker process is killed. The code is as follows

1     defmanage_workers (self):2         """3 Maintain the number of workers by spawning or killing4 As required.5         """6         ifLen (self. Workers.keys ()) <self.num_workers:7 self.spawn_workers ()8  9Workers =Self . Workers.items ()TenWorkers = sorted (workers, key=LambdaW:w[1].age)#Sort by worker's age order One          whileLen (Workers) > Self.num_workers:#Num_workers is the number of worker configured A(PID, _) =workers.pop (0) -Self.kill_worker (PID, signal. SIGTERM)

SIGUSR2

Upgrade The Gunicorn on the fly. A separate term signal should is used to kill the old process.

The corresponding signal processing function is arbiter.reexec, the function will fork out the new master-workers process, but will not affect the original Master,worker process, so the above mentioned need to kill the original process.

1     defreexec (self):2         """3 relaunch the master and workers.4         """5         ifSelf.reexec_pid! =0:6Self.log.warning ("USR2 signal ignored. Child exists.")7             return8  9         ifSelf.master_pid! =0:TenSelf.log.warning ("USR2 signal ignored. Parent exists") One             return A   -Master_pid =os.getpid () -Self.reexec_pid =os.fork () the         ifSelf.reexec_pid! =0: -             return -   - self.cfg.pre_exec (self) +   -Environ =self.cfg.env_orig.copy () +FDS = [L.fileno () forLinchSelf . LISTENERS] Aenviron['GUNICORN_FD'] =",". join ([STR (FD) forFdinchFDS]) # Some environment variables are set to distinguish between starting gunicorn normally or restarting with fork.  atenviron['Gunicorn_pid'] =Str (master_pid) -   -Os.chdir (self. start_ctx['CWD']) -   -         #exec the process using the original environnement -Os.execvpe (self. Start_ctx[0], self. start_ctx['args'], environ)

Below do the experiment, two terminal, terminal 1th running code, Terminal 2nd sends a signal. Step1: Terminal 1th start Gunirorn:gunicorn-w 2 Gunicorn_app:app, terminal 2nd looks at the Python process:ps-ef | grep python,  1 terminal output [2017-01-19 15:21:23 +0000] [6166] [info] starting gunicorn  19.6.0[2017-01-19 15:21:23 +0000] [6166] [info] listening at: http:// 127.0.0.1:8000  (6166) [2017-01-19 15:21:23 +0000] [6166] [info] using worker :  sync[2017-01-19 15:21:23 +0000] [6171] [info] booting worker with  pid: 6171[2017-01-19 15:21:23 +0000] [6172] [info] booting worker  WITH PID: 6172 2 Terminal Output hzliumi+  6166  5721  0 15:21  pts/0    00:00:00 /usr/bin/python /usr/local/bin/gunicorn -w 2  gunicorn_app:apphzliumi+  6171  6166  0 15:21 pts/0     00:00:00 /usr/bin/python /usr/local/bin/gunicorn -w 2 gunicorn_app: apphzliumi+  6172   6166  0 15:21 pts/0    00:00:00 /usr/bin/python /usr/local/ bin/gunicorn -w 2 gunicorn_app:app  can see that the PID of the master process is 6166 , then the PID of the two worker processes is 6171, 6172, respectively. The following PID is required for master process Step2: Terminal 2nd sends a signal:KILL-SIGUSR2 6166 , and then view the Python process  1 terminal append output [2017-01-19 15:27:08 +0000] [6166] [info] handling  Signal: usr2[2017-01-19 15:27:08 +0000] [6629] [info] starting gunicorn  19.6.0[2017-01-19 15:27:08 +0000] [6629] [info] listening at: http:// 127.0.0.1:8000  (6629) [2017-01-19 15:27:08 +0000] [6629] [info] using worker :  sync[2017-01-19 15:27:08 +0000] [6634] [info] booting worker with  pid: 6634[2017-01-19 15:27:08 +0000] [6635] [info] booting worker  WITH PID: 6635 2 Terminal Output hzliumi+  6166  5721  0 15:21  pts/0    00:00:00 /usr/bin/python /usr/local/bin/gunicorn -w 2  gunicorn_app:apphzliumi+  6171  6166  0 15:21 pts/0     00:00:00 /usr/bin/python /usr/local/bin/gunicorn -w 2 gunicorn_app:apphzliumi+  6172   6166  0 15:21 pts/0    00:00:00 /usr/bin/python /usr/ Local/bin/gunicorn -w 2 gunicorn_app:apphzliumi+  6629  6166  3  15:27 pts/0    00:00:00 /usr/bin/python /usr/local/bin/gunicorn  -w 2 gunicorn_app:apphzliumi+  6634  6629  0 15:27 pts/0     00:00:00 /usr/bin/python /usr/local/bin/gunicorn -w 2  gunicorn_app:apphzliumi+  6635  6629  0 15:27 pts/0     00:00:00 /usr/bin/python /usr/local/bin/gunicorn -w 2 gunicorn_app:app  As can be seen from Terminal 1th, the basic is to restart the Gunicorn, but from terminal 2nd output can be seen, The new master process (PID 6629) is a child of the old master process (PID 6166)   Step3: Terminal 2nd sends a signal:kill-sigterm 6166 , wait a few seconds to view the Python process:  1 terminal append output [2017-01-19 15:29:42 +0000] [6166] [info] handling  signal: term[2017-01-19 15:29:42 +0000] [6171] [info] worker exiting   (pid: 6171) [2017-01-19 15:29:42 +0000] [6172] [info] worker exiting   (pid: 6172) [2017-01-19 15:29:42 +0000] [6166] [info] shutting down:  Master[2017-01-19 15:29:42 +0000] [6629] [INFO] Master has been  PROMOTED. 2 Terminal Output hzliumi+  6629     1  0 15:27 pts/ 0    00:00:00 /usr/bin/python /usr/local/bin/gunicorn -w 2  gunicorn_app:apphzliumi+  6634  6629  0 15:27 pts/0     00:00:00 /usr/bin/python /usr/local/bin/gunicorn -w 2 gunicorn_app:apphzliumi+   6635 &nbsP;6629  0 15:27 pts/0    00:00:00 /usr/bin/python /usr/local /bin/gunicorn -w 2 gunicorn_app:app  can see that the old master process (6166) and its fork-out worker subprocess (PID is 6171, 6172) has been killed    references:http://docs.gunicorn.org/en/stable/signals.html

Gunicorn signal Processing (SIGHUP,SIGUSR2)