They use SIGWINCH for gracefully shutting down workers but not the main process [0]. SIGQUIT is used for a graceful shutdown and SIGTERM for a sort of graceful shutdown (with timeouts).
SIGWINCH is apparently used for an online upgrade [1]. Because it only shuts the workers down you can quickly transition back to the old binary and old configuration if there's a problem, even after upgrading the binary or config stored on the hard drive.
I'm sure there are other ways to get a similar capability, but this set of signals is apparently what they came up with.
SIGWINCH is apparently used for an online upgrade [1]. Because it only shuts the workers down you can quickly transition back to the old binary and old configuration if there's a problem, even after upgrading the binary or config stored on the hard drive.
I'm sure there are other ways to get a similar capability, but this set of signals is apparently what they came up with.
[0] http://nginx.org/en/docs/dev/development_guide.html#processe...
[1] https://www.digitalocean.com/community/tutorials/how-to-upgr...