Re: [gamin] 100% CPU in gam_server

[Daniel Veillard <veillard redhat com>]

On Thu, Nov 11, 2004 at 12:30:55AM +1100, Benjamin Lee wrote:
> Greets list,
> 
> Unfortunately, it is possible for gam_server to go 100% CPU crazy in
> gam_poll.c:remove_directory_subscription().
> 
> It seems the GList *children can sometimes contain a next-> loop and
> therefore the program will loop forever in:
> 
>  545     for (l = children; l; l = l->next) {
>  
> Bummer eh.
> 
> (gdb) list remove_directory_subscription
> Line 535 of "gam_poll.c" starts at address 0x804c6ad <remove_directory_subscription> and ends at 0x804c6b3 <remove_directory_subscription+6>.
> (gdb) 
> 
> I have seen this 100% CPU issue several times now... but I have not yet
> determined the steps to reproduce it. I just thought I'd give the list a
> heads up.
> 
> As for debugging, in the past I've macro-ed a GList check function that is
> run for *every* list action. It checks that the list has no loops... but
> traversing the list until next == NULL or 'n' and if 'n' is reached (where
> n is large like 100000) then we have a loop.
> 
> Other ideas?

  yeah, I know, it's really really anoying. I intend to make a complete 
reread of that part of the code and add the same loop checking to 
remove_directory_subscription() as I did in gam_poll_scan_directory_internal()
(which uses 2 pointer, it is an exact check and is faster than the solution
you suggest to catch them).

Daniel

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