On Wed, 2006-01-11 13:37:45 +0100, Gábor Lénárt <[email protected]> wrote: > Hello, > > The following problem may be simple for you, so I hope someone can answer > here. We've got a complex software using child processes and a table > to keep data of them together, like this: > > childs[n].pid=fork(); > > where "n" is an integer contains a free "slot" in the childs struct array. > > I also handle SIGCHLD in the parent and signal handler searches the childs > array for the pid returned by waitpid(). However here is my problem. The > child process can be fast, ie exits before scheduler of the kernel give > chance the parent process to run, so storing pid into childs[n].pid in the > parent context is not done yet. Child may exit, than scheduler gives control > to the signal handler before doing the store of the pid (if child run for > more time, eg 10 seconds it works of course). So it's impossible to store > child pids and search by that information in eg the signal handler? It's > quite problematic, since the code uses blocking I/O a lot, so other > solutions (like searching in childs[] in the main program and not in signal > handler) would require to recode the whole project. The problem can be > avoided with having a fork() run the PARENT first, but I thing this is done > by the scheduler so it's a kernel issue. Also the problem that source should > be portable between Linux and Solaris ... One way to sort this out would be to queue the dead childs to some thread that clears the child's slot, possibly waiting on a condition (queue to slot list ready). Quite easy :-) MfG, JBG -- Jan-Benedict Glaw [email protected] . +49-172-7608481 _ O _ "Eine Freie Meinung in einem Freien Kopf | Gegen Zensur | Gegen Krieg _ _ O für einen Freien Staat voll Freier Bürger" | im Internet! | im Irak! O O O ret = do_actions((curr | FREE_SPEECH) & ~(NEW_COPYRIGHT_LAW | DRM | TCPA));
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- From: Gábor Lénárt <[email protected]>
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