mod_fcgid: can't apply process slot

[Lars Noodén <lars.nooden@xxxxxxxxxxxxxxxxxxx>]

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


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