You are viewing a plain text version of this content. The canonical link for it is here.
Posted to users@httpd.apache.org by Lars Noodén <la...@gmx.com.INVALID> on 2025/06/09 09:36:09 UTC
[users@httpd] mod_fcgid: can't apply process slot
Hello,
I have a FastCGI script working with Apache2 on one system, but seem to
have missed something while trying to port it over to another system.
On the new system, the browser takes a long time before finally
returning a "503 Service Unavailable" message.
When that happens, the log file shows the following errors (indented
here for readability),
. . .
[Mon Jun 09 08:43:34.566447 2025] [fcgid:warn] [pid
1910852:tid 1910852] [client xx.yy.zz.aa:61458]
mod_fcgid: can't apply process slot for
/var/www/example.org/fcgi/x_test-00.fcgi
[Mon Jun 09 08:43:46.324188 2025] [fcgid:warn] [pid
1910900:tid 1910900] [client xx.yy.zz.aa:52592]
mod_fcgid: can't apply process slot for
/var/www/example.org/fcgi/x_test-00.fcgi
. . .
The script works fine on its own:
$ sudo -u www-data REQUEST_METHOD="GET" \
/var/www/example.org/fcgi/test.fcgi
Content-Type: text/plain
Hello, World! 0
I have the following in the Apache2 vhost for that site:
. . .
ScriptAlias /search/query /var/www/example.org/fcgi/test.fcgi
<Directory /var/www/example.org/fcgi>
Options +ExecCGI
AddHandler fcgid-script .fcgi
Order allow,deny
Allow from all
</Directory>
. . .
I have looked at the following for ideas,
https://httpd.apache.org/mod_fcgid/mod/mod_fcgid.html
I've tried modifying /etc/apache2/mods-available/fcgid.conf to increase
FcgidMaxProcesses and FcgidMaxProcessesPerClass to various large
numbers, and then reloading, but to no effect. That's probably barking
up the wrong tree, however.
What settings have I missed?
/Lars
---
$ /usr/sbin/apache2ctl -v
Server version: Apache/2.4.62 (Debian)
Server built: 2024-10-04T15:21:08
$ /sbin/a2query -m | sort
access_compat (enabled by maintainer script)
alias (enabled by maintainer script)
auth_basic (enabled by maintainer script)
authn_core (enabled by maintainer script)
authn_file (enabled by maintainer script)
authz_core (enabled by maintainer script)
authz_host (enabled by maintainer script)
authz_user (enabled by maintainer script)
autoindex (enabled by maintainer script)
cache (enabled by site administrator)
deflate (enabled by maintainer script)
dir (enabled by maintainer script)
env (enabled by maintainer script)
evasive (enabled by maintainer script)
fcgid (enabled by maintainer script)
filter (enabled by maintainer script)
headers (enabled by site administrator)
include (enabled by site administrator)
mime (enabled by maintainer script)
mpm_prefork (enabled by maintainer script)
negotiation (enabled by maintainer script)
reqtimeout (enabled by maintainer script)
rewrite (enabled by site administrator)
setenvif (enabled by maintainer script)
socache_shmcb (enabled by site administrator)
ssl (enabled by site administrator)
status (enabled by maintainer script)
$ lsb_release -rd
No LSB modules are available.
Description: Debian GNU/Linux 12 (bookworm)
Release: 12
---------------------------------------------------------------------
To unsubscribe, e-mail: users-unsubscribe@httpd.apache.org
For additional commands, e-mail: users-help@httpd.apache.org
Re: [users@httpd] mod_fcgid: can't apply process slot
Posted by Lars Noodén <la...@gmx.com.INVALID>.
On 6/9/25 12:36, Lars Noodén wrote:
> Hello,
>
> I have a FastCGI script working with Apache2 on one system, but seem to
> have missed something while trying to port it over to another system. On
> the new system, the browser takes a long time before finally returning a
> "503 Service Unavailable" message.
>
> When that happens, the log file shows the following errors (indented
> here for readability),
>
> . . .
> [Mon Jun 09 08:43:34.566447 2025] [fcgid:warn] [pid
> 1910852:tid 1910852] [client xx.yy.zz.aa:61458]
> mod_fcgid: can't apply process slot for
> /var/www/example.org/fcgi/x_test-00.fcgi
>
> [Mon Jun 09 08:43:46.324188 2025] [fcgid:warn] [pid
> 1910900:tid 1910900] [client xx.yy.zz.aa:52592]
> mod_fcgid: can't apply process slot for
> /var/www/example.org/fcgi/x_test-00.fcgi
> . . .
>
> The script works fine on its own:
>
> $ sudo -u www-data REQUEST_METHOD="GET" \
> /var/www/example.org/fcgi/test.fcgi
> Content-Type: text/plain
>
> Hello, World! 0
>
> I have the following in the Apache2 vhost for that site:
>
> . . .
> ScriptAlias /search/query /var/www/example.org/fcgi/test.fcgi
> <Directory /var/www/example.org/fcgi>
> Options +ExecCGI
> AddHandler fcgid-script .fcgi
>
> Order allow,deny
> Allow from all
> </Directory>
> . . .
>
> I have looked at the following for ideas,
>
> https://httpd.apache.org/mod_fcgid/mod/mod_fcgid.html
>
> I've tried modifying /etc/apache2/mods-available/fcgid.conf to increase
> FcgidMaxProcesses and FcgidMaxProcessesPerClass to various large
> numbers, and then reloading, but to no effect. That's probably barking
> up the wrong tree, however.
>
> What settings have I missed?
>
> /Lars
>
> ---
>
> $ /usr/sbin/apache2ctl -v
> Server version: Apache/2.4.62 (Debian)
> Server built: 2024-10-04T15:21:08
>
> $ /sbin/a2query -m | sort
> access_compat (enabled by maintainer script)
> alias (enabled by maintainer script)
> auth_basic (enabled by maintainer script)
> authn_core (enabled by maintainer script)
> authn_file (enabled by maintainer script)
> authz_core (enabled by maintainer script)
> authz_host (enabled by maintainer script)
> authz_user (enabled by maintainer script)
> autoindex (enabled by maintainer script)
> cache (enabled by site administrator)
> deflate (enabled by maintainer script)
> dir (enabled by maintainer script)
> env (enabled by maintainer script)
> evasive (enabled by maintainer script)
> fcgid (enabled by maintainer script)
> filter (enabled by maintainer script)
> headers (enabled by site administrator)
> include (enabled by site administrator)
> mime (enabled by maintainer script)
> mpm_prefork (enabled by maintainer script)
> negotiation (enabled by maintainer script)
> reqtimeout (enabled by maintainer script)
> rewrite (enabled by site administrator)
> setenvif (enabled by maintainer script)
> socache_shmcb (enabled by site administrator)
> ssl (enabled by site administrator)
> status (enabled by maintainer script)
>
> $ lsb_release -rd
> No LSB modules are available.
> Description: Debian GNU/Linux 12 (bookworm)
> Release: 12
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: users-unsubscribe@httpd.apache.org
> For additional commands, e-mail: users-help@httpd.apache.org
Thanks to those who read the first message.
After some adjustments, I started getting the following error instead
which led to finding a work-around:
[Thu Jun 19 11:25:22.899742 2025] [fcgid:error] [pid 2824873:tid
2824873] (13)Permission denied: mod_fcgid: couldn't bind unix domain
socket /var/lib/apache2/fcgid/sock/2824873.59
It turns out that on this other system, Apache2 has a non-default user
set for that (and another) vhost via the User directive. A work-around
seems to be to change the ownership of /var/lib/apache2/fcgid/sock/ from
the default Apache2 user to the account specified by the User directive
for that vhost. This is not a permanent solution because there can be
more vhosts each with custom User/Group directives, assuming the sockets
directory persists across reboots.
The sockets directory seems to have been created by the package
libapache2-mod-fcgid:
$ dpkg -S /var/lib/apache2/fcgid/sock/
libapache2-mod-fcgid: /var/lib/apache2/fcgid/sock
Perhaps this quirk is a bug in Debian's package for Apache2's fcgi
module in Debian because it is not reading the vhosts' User/Group
settings.
In my case those User + Group directives have been set per-vhost in the
individual vhosts' configuration files while /etc/apache2/envvars still
contains the default.
$ grep -R '^User ' /etc/apache2/sites-available/*.conf | wc -l
4
$ grep -R www-data /etc/apache2/
/etc/apache2/envvars:export APACHE_RUN_USER=www-data
/etc/apache2/envvars:export APACHE_RUN_GROUP=www-data
So the installer would have to look in more than just
/etc/apache2/envvars and the three places which would have to be aware
of vhost settings are in debian/libapache2-mod-fcgid.postinst,
debian/rules, or debian/tests/perl. I'll have to think on it.
Maybe FcgidIPCDir can be set on a per-vhost basis?
/Lars
PS. Speaking of possible bugs, I notice that the mailing list appends
the suffix .INVALID to my e-mail address, oddly.
---------------------------------------------------------------------
To unsubscribe, e-mail: users-unsubscribe@httpd.apache.org
For additional commands, e-mail: users-help@httpd.apache.org