If you have two (or more) instances of gunicorn that use `reuse-port`
and bind to single unix socket all work until one of gunicorn will
stopped. Because the first stopped removes unix socket file and other
instances can't longer process requests.
Track the use of systemd socket activation and gunicorn socket inheritance
in the arbiter. Unify the logic of creating gunicorn sockets from each of
these sources to always use the socket name to determine the type rather
than checking the configured addresses. The configured addresses are only
used when there is no inheritance from systemd or a parent arbiter.
Fix#1298
This is similar to worker_exit() in that it is called just after a
worker has terminated, but it's called in the Gunicorn *master* process,
not the *child* process.
This changes improve the binary upgrade behaviour using USR2:
- only one binary upgrade can happen at a time: the old arbiter needs to be
killed to promote the new arbiter.
- if a new arbiter is already spawned, until one is killed USR2 has no action
- if a new arbiter has been spawned, the unix socket won't be unlinked
- until the old arbiter have been killed the newly created pidfile has the name
<pidfile>.2 and the name Master.2 .
Note: there is no dialog between both arbiters to handle this features.
Instead they will supervise each others until one is killed. So isolation is
still guaranted.
fix#1267
This change add proper file locking to gunicorn. By default "gunicorn.lock" is created in the temporary directory when a unix socket is bound. In case someone want to fix the lock file path or use multiple gunicorn instance the "--lock-file" setting can be used to set the path of this file.
fix#1259
Close all the listeners when the arbiter shuts down. By doing so,
workers can close the socket at the beginning of a graceful shut
down thereby informing the operating system that the socket can
be cleaned up. With this change, graceful exits with such workers
will refuse new connections while draining, allowing load balancers
to respond more quickly and avoiding leaving connections dangling
in the listen backlog, unaccepted.
Ref #922
