[PATCH] Don't send MSG_WINBIND_ONLINE to idmap_child() in any child process

[boyang]

boyang wrote:
> Jeremy Allison wrote:
>   
>> On Tue, Jan 13, 2009 at 05:59:39PM +0800, boyang wrote:
>>   
>>     
>>> Hi, everyone:
>>>      If the trusted domain cannot go online, fork_child_dc_connect()
>>> will be invoked periodically to fork() one child process, trying to
>>> connect to DC.  look, fork_child_dc_connect() ---> getdcs() --->
>>> get_dc_name_via_netlogon() ---> cm_connect_netlogon() --->
>>> init_dc_connection() ---> cm_open_connection ---> set_domain_online(),
>>> here send MSG_WINBIND_ONLINE to idmap_child(). It causes
>>> MSG_WINBIND_ONLINE being sent to idmap_child() periodically, which cause
>>> idmap child to fork and connect to the primary domain'DC even primary
>>> domain is already online. :-)  It is very expensive, we must not want to
>>> do that....
>>>
>>> Please review the patches!
>>>     
>>>       
>> Ok, I've reviewed this very carefully, and I think you're
>> correct in this. I've broadened your patch slightly to add
>> code to null out the pid on all children after fork, as no
>> child should be sending messages to each other, it should
>> always go through the parent. Can you check this patch (designed
>> for 3-2-test) out and let me know if it works for you (should
>> do - it's a simple change to your code).
>>   
>>     
> I am thinking if we can decrease attempts to connect to DC further.
> Currently, both the parent and the child are trying to connect to DCs
> periodically, if domain cannot be brought online. Why not we just try to
> connect to DCs in parent, and if the parent can bring the DC online, it
> sends MSG_WINBIND_ONLINE to child? And when domain in child process goes
> offline, child sends MSG_WINBIND_OFFLINE to parent. This is not
> difficult, we can add one global variable and set it to true in parent
> process, then set it to false after fork. Then, all
> set_domain_online_request() can be eliminated from fork_domain_child().
>
> If we are in parent, set_domain_online() will sent ONLINE message to
> child of the domain. set_domain_offline() just set domain offline, don't
> set any message to child.
>
> If we are in child, set_domain_online just set the domain online, don't
> sent any messages to parent. set_domain_offline() set the domain offline
> and sends OFFLINE message to parent.
>
> Then, only parent tries to connect to DCs periodically.
>
> With this, we can decrease the attempts to connect to DCs by half when
> network is unreachable.
>
> If this is worth to do, I'll do it. :-)
>   
Oh, parent must send OFFLINE to child, this will incur loops..... We
have to define some more MSG_ to handle it....
>> Once I get confirmation I'll commit to all branhes under
>> your name, thanks !
>>
>> Jeremy.
>>
>>   
>>     

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