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Posted to bugs@httpd.apache.org by bu...@apache.org on 2016/01/04 18:29:59 UTC
[Bug 58799] New: mod_fcgid: FcgidMinProcessesPerClass doesn't seem
to work
https://bz.apache.org/bugzilla/show_bug.cgi?id=58799
Bug ID: 58799
Summary: mod_fcgid: FcgidMinProcessesPerClass doesn't seem to
work
Product: Apache httpd-2
Version: 2.4.18
Hardware: PC
OS: Linux
Status: NEW
Severity: normal
Priority: P2
Component: mod_fcgid
Assignee: bugs@httpd.apache.org
Reporter: burnettk+apachebugzilla@gmail.com
Greetings,
I received no resolutions to my issue--and no one reporting that
FcgidMinProcessesPerClass works for them--on the mailing list,
http://www.gossamer-threads.com/lists/apache/users/453417?do=post_view_threaded,
so I'm following up with a bug report.
If I set FcgidMinProcessesPerClass to 5, it doesn't maintain 5 application
worker processes at apache startup time or otherwise. It starts with 0 workers,
then when I hit the app with one curl, it starts up one, and when I hit the app
with 10 concurrent connections, it fires up more workers. Keeping the count
below a defined limit via FcgidMaxProcessesPerClass seems to work fine. But its
sister property, FcgidMinProcessesPerClass, documented at
http://httpd.apache.org/mod_fcgid/mod/mod_fcgid.html#fcgidminprocessesperclass,
doesn't behave as I would expect.
I'm running a rails 4.2 app on apache 2.4.18, mod_fcgid 2.3.9, and ubuntu
14.04.3. I created this docker project to demonstrate what I'm seeing:
https://github.com/burnettk/repro-mod-fcgid-bug/blob/master/README.md. It has
replication steps in the README and you can dig around in the github project or
actually fire up the docker container following the steps in the README and
inspect all of the configs.
Thanks!
KB
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[Bug 58799] mod_fcgid: FcgidMinProcessesPerClass doesn't seem to work
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=58799
--- Comment #9 from Tomaž Šolc <to...@tablix.org> ---
Why have the bot say "please reopen this ticket if still relevant" when it's
just going to be instant re-closed without as much courtesy as a word from a
human?
You "appreciate" me taking the time to write up a report and submit a patch
those years ago indeed. I could just not bother. Probably I'm the only one
still running (and patching) mod_fcgid today any way.
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[Bug 58799] mod_fcgid: FcgidMinProcessesPerClass doesn't seem to
work
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=58799
--- Comment #2 from burnettk+apachebugzilla@gmail.com ---
Thanks for the clarification. I am not seeing that a request causes a new
worker to be spawned if the current count is below this value (mine is set to
5). I can curl my app all day long with one request at a time, and the current
count stays at one worker. :) This is presumably because the one worker handles
all of the requests. I'm guessing your statement ("The effect of
FcgidMinProcessesPerClass is to guarantee that a request will cause a new
worker to be spawned if the current count is below this value") is qualified by
"if an existing worker cannot handle the request."
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[Bug 58799] mod_fcgid: FcgidMinProcessesPerClass doesn't seem to work
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=58799
Tomaž Šolc <to...@tablix.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|WONTFIX |---
Status|RESOLVED |REOPENED
--- Comment #8 from Tomaž Šolc <to...@tablix.org> ---
The bug report and attached patch are still relevant for mod_fcgid 2.3.9 (still
the last release according to https://httpd.apache.org/mod_fcgid/) and Apache
2.4.67.
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[Bug 58799] mod_fcgid: FcgidMinProcessesPerClass doesn't seem to work
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=58799
Rich Bowen <rb...@apache.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |WONTFIX
Status|NEW |RESOLVED
--- Comment #7 from Rich Bowen <rb...@apache.org> ---
Thank you for your report. As part of an effort to clean up our issue tracker,
we are closing tickets that have seen no activity for more than 5 years. If
this issue is still relevant to a current version of Apache httpd (2.4.x or
trunk), please reopen this ticket or open a new one with updated information.
We appreciate your contribution to the project.
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[Bug 58799] mod_fcgid: FcgidMinProcessesPerClass doesn't seem to
work
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=58799
Tomaž Šolc <to...@tablix.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |tomaz.solc@tablix.org
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[Bug 58799] mod_fcgid: FcgidMinProcessesPerClass doesn't seem to
work
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=58799
Artem Russakovskii <ar...@gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |archon810@gmail.com
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[Bug 58799] mod_fcgid: FcgidMinProcessesPerClass doesn't seem to
work
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=58799
--- Comment #5 from Tomaž Šolc <to...@tablix.org> ---
Created attachment 33869
--> https://bz.apache.org/bugzilla/attachment.cgi?id=33869&action=edit
workaround in scan_idlelist() to always respect FcgidMinProcessesPerClass
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[Bug 58799] mod_fcgid: FcgidMinProcessesPerClass doesn't seem to
work
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=58799
--- Comment #1 from Dominic Benson <do...@thirdlight.com> ---
The effect of FcgidMinProcessesPerClass is to guarantee that a request will
cause a new worker to be spawned if the current count is below this value. It
won't (and shouldn't) keep workers beyond their configured allowed lifetime.
Sadly it can't proactively spawn a new worker.
I can't just recall when this was last discussed, but the gist is that there
isn't currently a mechanism to spawn a worker without also sending it a
request.
The description in the docs "This directive sets the minimum number of
processes that will be retained in a process class after finishing requests."
is correct in not intimating that processes will be created at startup, however
it could perhaps benefit from an addendum to the effect that other directives
may prevent a worker from being retained indefinitely.
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[Bug 58799] mod_fcgid: FcgidMinProcessesPerClass doesn't seem to work
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=58799
vitoriabernard101@gmail.com changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|REOPENED |RESOLVED
Resolution|--- |FIXED
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[Bug 58799] mod_fcgid: FcgidMinProcessesPerClass doesn't seem to
work
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=58799
--- Comment #3 from Dominic Benson <do...@thirdlight.com> ---
That isn't what I meant when I wrote it, but it does appear to be true (it's
been a while since I looked at the process count management code)!
In https://bz.apache.org/bugzilla/show_bug.cgi?id=53693 I posted a patch which
makes process spawning more eager below the min process count - it isn't enough
for the behaviour you're expecting on its own.
(https://bz.apache.org/bugzilla/show_bug.cgi?id=52174 is also a closely related
issue.)
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[Bug 58799] mod_fcgid: FcgidMinProcessesPerClass doesn't seem to
work
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=58799
--- Comment #6 from Tomaž Šolc <to...@tablix.org> ---
For what is worth, the attached patch makes scan_idlelist() only kill one
process per run. This works around the problem with out-of-date process count
in is_kill_allowed(), but makes FCGI kill at most one process per
IdleScanInterval.
As far as I can see, mod_fcgid with this patch correctly respects the
FcgidMinProcessesPerClass setting. This workaround is useful if you want to
error on the side of too many idle workers rather than too few (for instance if
the worker startup time is very high).
I'm using Apache 2.4.10 and fcgid 2.3.9, as packaged for Debian Jessie.
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[Bug 58799] mod_fcgid: FcgidMinProcessesPerClass doesn't seem to
work
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=58799
--- Comment #4 from Tomaž Šolc <to...@tablix.org> ---
Hi
I'm also seeing unexpected behavior regarding the FcgidMinProcessesPerClass
setting. In a test environment, if I momentarily load a server, it will
correctly spawn many (i.e. more than FcgidMinProcessesPerClass) workers, but
after FcgidIdleTimeout, it will also kill all of them (server-status page says
"Exiting (idle timeout)"). However, in practice, I usually see between 0 and
FcgidMinProcessesPerClass processes running, even if idle times of some of them
are above FcgidIdleTimeout.
Documentation for FcgidIdleTimeout says that "Application processes [...] will
be terminated, if the number of processes for the class exceeds
FcgidMinProcessesPerClass". From this I expect that idle timeout will not kill
all idle processes, but only kill as many as necessary to keep at least
FcgidMinProcessesPerClass processes running.
Looking at the source: idle timeout for processes is detected in
scan_idlelist(). This then checks number of running processes against
FcgidMinProcessesPerClass in is_kill_allowed(). It seems to me the problem is
that the process count is not updated while processes are selected for
termination in scan_idlelist(). The count in current_node->process_counter is
only updated later in a second pass, when the processes are actually killed in
scan_errorlist().
This is consistent with the behavior I'm seeing. After bursty loads, you will
have all processes reach the idle timeout at once. Process count will be above
FcgidMinProcessesPerClass and all will be killed. With more random loads, you
will have idle processes reach the timeout at different times, meaning process
count will be updated between each run of the scan_idlelist().
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[Bug 58799] mod_fcgid: FcgidMinProcessesPerClass doesn't seem to
work
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=58799
Artem Russakovskii <ar...@gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC|archon810@gmail.com |
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[Bug 58799] mod_fcgid: FcgidMinProcessesPerClass doesn't seem to work
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=58799
Rich Bowen <rb...@apache.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|FIXED |---
Status|RESOLVED |REOPENED
--- Comment #10 from Rich Bowen <rb...@apache.org> ---
Sorry, I'm unclear who closed this ticket. The account that closed it is
unfamiliar to me. Reopening.
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