util_ldap_cache & shared memory failure

[Bennett, Tony - CNF]

Title: Message

Graham,

 

Is the problem I reported at the bottom the same as

the problem you reported on 12-09-02, in this posting

and if so did you fix it?

List:     apache-httpd-dev
Subject:  mod_ldap and threaded MPMs
From:     Graham Leggett <minfrin () sharp ! fm>
Date:     2002-12-09 8:46:01

Hi all,

When httpd is compiled with the worker MPM (threaded), mod_ldap's
connection pool fails - many connections to the LDAP server are opened
until connections run out. The prefork MPM seems to work fine.

I don't have much time this week to look at this, if someone who knows
threads and locking could look at this I would be very grateful :)

Regards,
Graham
--
-----------------------------------------
[EMAIL PROTECTED] "There's a moon
over Bourbon Street
tonight..."

-Tony

-----Original Message-----
From: Bennett, Tony - CNF [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, December 18, 2002 2:44 PM
To: '[EMAIL PROTECTED]'
Cc: [EMAIL PROTECTED]
Subject: [Auth_ldap] util_ldap_cache & shared memory failure

Sorry for the cross post, but I'm not sure which group
is appropriate.

I am getting the following message in my apache error log

        [Wed Dec 18 11:23:18 2002] [debug] util_ldap_cache.c(307): (17)Do not specify an existing file.

I believe I have tracked this down to a problem with util_ldap_cache.c.

util_ldap.c has registered its util_ldap_init_module() function to be called
during "child_init" as follows:

        ap_hook_child_init(util_ldap_init_module, NULL, NULL, APR_HOOK_MIDDLE);

util_ldap_init_module() in turn calls util_ldap_cache_init() (contained in util_ldap_cache.c).

util_ldap_cache_init() tries to create a shared memory segment by calling apr_shm_create()
as follows:
         result = apr_shm_create(&util_ldap_shm, reqsize, "/tmp/ldap_cache", pool);

This call fails for all but the first time it is called... with the message shown at the top.
The failure causes util_ldap_cache_init() to return immediately... and not complete the function. 
The failure is because apr_shm_create() expects the file, "/tmp/ldap_cache", to be non-existent...
...and it will create it... if it exists, then the function fails.

If I'm not mistaken, I don't believe the shared memory should be "created"  for each child.

Using mod_auth_digest, and mod_ssl as a model... it appears it should be created in a
ap_hook_post_config() hook. 

Does this seem correct???

Here's my Environment:
        Version:        Apache 2.0.42
        OS:             AIX 4.3.3
        Compiler:       IBM C for AIX version 6.0

Thanks,
-tony