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Date: Mon, 15 Oct 2007 12:49:01 -0700 (PDT)
From: Marin Cosmin <marincosmin2001@yahoo.com>
Subject: Re: [Unload module]
To: modules-dev@httpd.apache.org
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Message-ID: <812162.9999.qm@web60315.mail.yahoo.com>

Thank you very much for your promptness.=0A=0AI've tested and segfaults if =
I unload the module. In order to resolve this problem I use a flag which is=
 true if everything went fine, and false if didn't, but I thought that you =
can unload the module if something goes wrong.=0A=0AI'm  using "post_config=
" to initialize some structures some of them=0Abased on the configuration r=
ead form httpd.conf . Here is the place=0Awhere I get some shared memory, a=
nd mutex. In the same hook I=0Aused  apr_pool_cleanup_register but doesn't =
work. After apache exits "ipcs" command shows my shm & mutex. ipcrm helps t=
o clear IPCs. =0A=0A=0AIndeed all IPC used by children, after exit are free=
d (due to apr_pool_cleanup_register), but the main process, the parent of t=
hese children doesn't de-allocates & destroies the shm segment for example.=
 The children only detach the sahred memory, but the main process should de=
stroy it. This segment is created by main httpd process at startup and used=
 by all other httpd's children.=0A=0ASorry if I'm not very clear ...=0A=0AM=
y problem is that I don't know how to make the main httpd process, which ru=
ns as root,  to dealocate some IPC at exit, that were created at its startu=
p.=0A=0AThank you again.=0A=0AHave I nice day!=0A=0A----- Original Message =
----=0AFrom: Joe Lewis <joe@joe-lewis.com>=0ATo: modules-dev@httpd.apache.o=
rg=0ASent: Monday, October 15, 2007 9:04:35 PM=0ASubject: Re: [Unload modul=
e]=0A=0A=0AMarin Cosmin wrote:=0A> Hello,=0A>=0A> I'm working on an Apache =
module that will log some statistics in a=0A file.=0A> My problem is that I=
 have no ideea about what should I do to unload=0A the module.=0A> In ap_ho=
ok_post_config hook I initialize some structures, use open()=0A for some fi=
les ...=0A> If I get an error during this phase how can I unload the module=
 ?=0A>=0A>   =0A=0AI'm not sure that unloading the module is a good idea. I=
'd suggest=0A using=0Aone of the *open_logs or *post_config hooks - and ret=
urn an appropriate=0Aerror code if failure occurs. If you find that apache =
continues to=0A load,=0Athen you may want to set a flag in a configuration =
structure that you=0Acan use to determine if you had success earlier. (For =
example, so that=0Ayou don't try to write statistics to a file that failed =
to open=0A earlier).=0A=0A> Where should I destroy IPCS ? =0A> I used apr_p=
ool_cleanup_register here but the behaviuor isn't the=0A desired one.=0A>=
=0A> Using apr_pool_cleanup_register in ap_hook_child_init seems to work.=
=0A>   =0A=0AThat is where you want it - when the child starts, each child =
needs to=0Abe able to clean up after itself, hence wait until the child sta=
rts to=0Aregister that one.=0A=0AThis is a bit more clear when comparing wo=
rker vs. prefork MPM's - each=0Achild process has to take care of it's own =
in order to prevent memory=0Aleaks, etc.=0A=0AJoe=0A-- =0AJoseph Lewis <htt=
p://sharktooth.org/>=0A"Divide the fire, and you will sooner put it out." -=
 Publius Syrus=0A=0A=0A=0A=0A=0A       =0A_________________________________=
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 a piece of cake. Yahoo! Small Business gives you all the tools to get onli=
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