[Adium-devl] rev 19069 - in branches/adium-1.0/Plugins/Gaim Service: . Libgaim.framework/Versions/A/Headers

[Graham Booker]

On Feb 24, 2007, at 8:33 PM, Evan Schoenberg wrote:

>
> On Feb 24, 2007, at 9:16 PM, Peter Hosey wrote:
>
>> On Feb 24, 2007, at 15:21:40, Evan Schoenberg wrote:
>>> dnssrv still uses fork()... I don't know if it creates zombies,  
>>> too, or not.
>>
>> Only if it doesn't call some member of the wait(2) family.
>>
>> x-man-page://2/wait (in case anyone needs it)
>
> No member of the wait() family is called in dnssrv.c... is standard  
> practice that it should be used somewhere, then?
>

There are 3 ways to fix this.
1) Use a double fork method, where the child forks again and then  
immediately exist.  The parent can block on a wait here because all  
the first child does before exit is a fork.  This means the child of  
the child has its parent exit, and so it then becomes the child of  
init (or I expect launchd in OS X), which calls wait periodically.   
This method is the care-free method.
2) The parent has a signal handler which detects a child's exit and  
handles it appropriately. (This is the zombie killer).
3) The parent calls wait when the child exist.

I suggest we do number 3 here.  Unlike the DNS lookups, we know  
exactly when the child exist.  The DNS lookups re-use the children to  
do more lookups later, so the exact time of the child's death is not  
known, but here, one lookup is done, and then child sends its data,  
cleans up its memory, then exits.  The parent then proceeds to read  
all its data.  If the parent simply calls wait at this point, it will  
catch the child's death.  It would need to store the pid in the  
_GaimSrvQueryData struct or something, so it can call waitpid and  
make sure it gets the correct one.  I could code this up pretty  
quickly this afternoon if you like.

> -Evan


- Graham


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