Date: Sun, 26 Jun 2022 19:46:40 -0400 From: Karl Denninger <karl@denninger.net> To: freebsd-hackers@freebsd.org Subject: Programing question regarding FCGI apps (in "C") Message-ID: <7c96bf50-42d1-b799-ec8d-146e26f1f014@denninger.net>
next in thread | raw e-mail | index | archive | help
This is a cryptographically signed message in MIME format.
--------------ms080304010900090100080303
Content-Type: multipart/alternative;
boundary="------------w9EMxmDxfOVQz0PHHO0peT0M"
--------------w9EMxmDxfOVQz0PHHO0peT0M
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
I have an application that has been a "traditional" CGI app for a long
time and am converting it to use the fcgi-dev "wrapper" under Apache
along with writing a little program that manages the daemons (so if
something goes wrong they get restarted with logging to the admin, I can
issue a kill to all of them to update the code or a restart request, etc.)
What I found is that with that wrapper in use the code runs fine -- but
it leaks memory. It is quite complex and uses the libpq library to talk
to Postgres, but I've never seen problems with libpq leaking memory
before. Nonetheless I spent the rather-considerable time to make darn
sure via wrapper functions that I wasn't leaking memory through
inappropriate use of malloc/realloc/free or unpaired calls to the libpq
functions that create allocations, including using wrappers to maintain
a list of "active" allocations and outstanding requests, checking for
dangling file handles, pollution of sentinel space in malloc'd memory
and similar, tossing any discontinuities in the syslog if it finds any.
The code is clean and when it comes back for the next "accept()" there's
nothing outstanding.
This implies that either libpq has a problem or the fastcgi wrapper
library does. The former I've used a great deal over a long period of
time (years) and have never had it cause trouble. The application does
some "straight through" stuff out of cron as well and there I can run
valgrind against it, which I have and there are no complaints with it
unable to find any dangling allocations -- albeit not every function
that is used in serving web requests in that library is used in the cron
job.
That leaves the fastcgi wrapper library. There is a caution in there
about anything that modifies the environment; I removed all the
setproctitle() calls which I use to identify status and such, and there
are no calls to setenv or putenv anywhere, nor any attempts to write
back to any of the environment pointers -- that much I'm quite sure of.
Anyone seen anything like this? For obvious reasons this is not good
behavior but tracking it down has proved elusive.
Thanks in advance!
--
Karl Denninger
karl@denninger.net
/The Market Ticker/
/[S/MIME encrypted email preferred]/
--------------w9EMxmDxfOVQz0PHHO0peT0M
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: 8bit
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
</head>
<body>
<p>I have an application that has been a "traditional" CGI app for a
long time and am converting it to use the fcgi-dev "wrapper" under
Apache along with writing a little program that manages the
daemons (so if something goes wrong they get restarted with
logging to the admin, I can issue a kill to all of them to update
the code or a restart request, etc.)</p>
<p>What I found is that with that wrapper in use the code runs fine
-- but it leaks memory. It is quite complex and uses the libpq
library to talk to Postgres, but I've never seen problems with
libpq leaking memory before. Nonetheless I spent the
rather-considerable time to make darn sure via wrapper functions
that I wasn't leaking memory through inappropriate use of
malloc/realloc/free or unpaired calls to the libpq functions that
create allocations, including using wrappers to maintain a list of
"active" allocations and outstanding requests, checking for
dangling file handles, pollution of sentinel space in malloc'd
memory and similar, tossing any discontinuities in the syslog if
it finds any. The code is clean and when it comes back for the
next "accept()" there's nothing outstanding.</p>
<p>This implies that either libpq has a problem or the fastcgi
wrapper library does. The former I've used a great deal over a
long period of time (years) and have never had it cause trouble.
The application does some "straight through" stuff out of cron as
well and there I can run valgrind against it, which I have and
there are no complaints with it unable to find any dangling
allocations -- albeit not every function that is used in serving
web requests in that library is used in the cron job.</p>
<p>That leaves the fastcgi wrapper library. There is a caution in
there about anything that modifies the environment; I removed all
the setproctitle() calls which I use to identify status and such,
and there are no calls to setenv or putenv anywhere, nor any
attempts to write back to any of the environment pointers -- that
much I'm quite sure of.</p>
<p>Anyone seen anything like this? For obvious reasons this is not
good behavior but tracking it down has proved elusive.</p>
<p>Thanks in advance!<br>
</p>
<div class="moz-signature">-- <br>
Karl Denninger<br>
<a href="mailto:karl@denninger.net" class="moz-txt-link-freetext">karl@denninger.net</a><br>
<i>The Market Ticker</i><br>
<font size="-2"><i>[S/MIME encrypted email preferred]</i></font></div>
</body>
</html>
--------------w9EMxmDxfOVQz0PHHO0peT0M--
--------------ms080304010900090100080303
Content-Type: application/pkcs7-signature; name="smime.p7s"
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="smime.p7s"
Content-Description: S/MIME Cryptographic Signature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--------------ms080304010900090100080303--
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?7c96bf50-42d1-b799-ec8d-146e26f1f014>