On 3/13/22 19:49, Dave Blanchard wrote:
On Sun, 13 Mar 2022 18:38:05 -0400 Alex Rousskov wrote:
kill -9 will not kill SMP Squid workers and other kid
processes. To a large degree, Squid will just keep running as if nothing
happened -- that signal cannot be caught and processed specially by the
receiving Squid process. Do not use "kill -9 `cat pidfile`" if you are
using SMP Squids!
It turns out double kill with a SIGTERM, besides being rather
inelegant, doesn't do the job either. It takes its sweet ass time--a
few seconds--to exit.
If you do not want Squid to wait for shutdown_lifetime to let some
pending transactions finish, then use "squid -k interrupt" (or SIGINT if
you want to work around unsupported invalid configuration files). That
shutdown procedure does not have a delay.
Who said I wanted the proxy, busy or not, to keep running and finish
what it's doing? The entire point is for it to stop IMMEDIATELY!
ESPECIALLY if it's currently busy!
Squid supports a variety of shutdown procedures that accommodate many
realistic use cases. The better you specify what _you_ want, the better
we can help you achieve those results. Your original email did not say
that you wanted Squid to stop IMMEDIATELY, and your followup email was
concerned with "any harm", so Amos suggested a graceful shutdown mode,
probably (very reasonably IMO!) assuming that you want to minimize harm.
So is there a signal that can be sent which is the exact equivalent
of squid -k interrupt?
Yes, "squid -k interrupt" uses SIGINT.
Why, oh why, does the config file have to be 100% valid
I believe I have already answered that loaded question. If something is
not clear in my answer, please feel free to ask followup questions, but
we should not go in circles.
What is actual use of the pidfile to the end user
I think there are two ways to answer this question:
* None: The PID file is not meant to be used by the end user. You may
use it at your own risk (e.g., if you want to work around unsupported
invalid configuration files), but such use is just an unsupported hack.
* The actual use of the PID file is to send a (supported) signal to the
running Squid instance without executing the Squid binary, with all the
conveniences and problems such executions may bring.
I am not sure what the official Squid Project position is regarding end
user use of the PID file. Such an official position may not exist (yet),
but I suspect it is currently closer to the first bullet because we do
not disclose/document which signals are used by various "squid -k" commands.
HTH,
Alex.
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