| commit | 5e3d05997769dd270123b9c2479938704de078de | |
| author | Eric Wong <e@80x24.org> | |
| Wed, 3 Jul 2019 23:34:31 +0000 (3 23:34 +0000) | ||
| committer | Eric Wong <e@80x24.org> | |
| Wed, 3 Jul 2019 23:34:31 +0000 (3 23:34 +0000) | ||
| tree | 8692b46b89a0e1481703c6a1c6b0c8b5b8182f57 | treesnapshot (tar.gz zip) |
| parent | 2ea6af4ed1ce5f3a34bdfd32b9e54a67fabcff26 | commitdiff |
examples/unicorn@.service: note the NonBlocking flag
It's racy otherwise when starting simultaneous instanced units.
Without specifying NonBlocking=true, systemd will clear the
O_NONBLOCK flag every time it starts a new service instance.
There's a small window where systemd can clear O_NONBLOCK
immediately after it's set by Ruby (or kgio):
unicorn@1 |systemd |unicorn@2
---------------------------+----------------+--------------------
F_SETFL, O_NONBLOCK|O_RDWR | | (not running, yet)
|F_SETFL, O_RDWR |
|fork |
| exec unicorn@2 |
accept4(...) # blocks! | | (now started by systemd)
| |F_SETFL,O_NONBLOCK|O_RDWR
| |accept4(...) non-blocking
It's racy otherwise when starting simultaneous instanced units.
Without specifying NonBlocking=true, systemd will clear the
O_NONBLOCK flag every time it starts a new service instance.
There's a small window where systemd can clear O_NONBLOCK
immediately after it's set by Ruby (or kgio):
unicorn@1 |systemd |unicorn@2
---------------------------+----------------+--------------------
F_SETFL, O_NONBLOCK|O_RDWR | | (not running, yet)
|F_SETFL, O_RDWR |
|fork |
| exec unicorn@2 |
accept4(...) # blocks! | | (now started by systemd)
| |F_SETFL,O_NONBLOCK|O_RDWR
| |accept4(...) non-blocking
| examples/unicorn@.service | diffblobblamehistory |