On Sun, Jul 4, 2010 at 6:45 PM, Matthew Flatt <mfl...@cs.utah.edu> wrote: > At Sun, 4 Jul 2010 16:26:21 -0400, Eli Barzilay wrote: >> On Jul 4, Matthew Flatt wrote: >> > [...] >> > >> > * A subprocess can create any number of sub-subprocesses itself, and >> > there's no way to kill those, which isn't very custodian-like. >> >> Isn't a process group the way to solve this? > > My impression from looking into this before was that process groups > don't help. Can't a subprocess just declare itself to be a new process > group (and there's no hierarchy)?
>From the wikipedia article on process groups: "Process groups are themselves grouped into sessions. Process groups are not permitted to migrate from one session to another, and a process may only create new process groups belonging to the same session as it itself belongs to. Processes are not permitted to join process groups that are not in the same session as they themselves are." I can't figure out if you can send a signal to every process group in a session, but you could emulate that (maybe) by iterating over all the processes. However, you can't ever be guaranteed to kill all the subprocesses, regardless of process groups. The subprocess could be setuid, and thus unkillable by the original Racket process. >From a best effort perspective, I think sending the signal to the process group is more custodian-like. -- sam th sa...@ccs.neu.edu _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
