I'm down to 9 places in the code that can produce unwaited for zombies.
Most of these are pretty innocuous, at least for now, are only
used in short-running commands, or commands that run a set of
actions and explicitly reap zombies after each one.
The one from Annex.Branch.files could be trouble later,
since both Command.Fsck and Command.Unused can trigger it,
and the assistant will be doing those eventally. Ditto the one in
Git.LsTree.lsTree, which Command.Unused uses.
The only ones currently affecting the assistant though, are
in Git.LsFiles. Several threads use several of those.
(And yeah, using pipes or ResourceT would be a less ad-hoc approach,
but I don't really feel like ripping my entire code base apart right
now to change a foundation monad. Maybe one of these days..)
Make Utility.Process wrap the parts of System.Process that I use,
and add debug logging to them.
Also wrote some higher-level code that allows running an action
with handles to a processes stdin or stdout (or both), and checking
its exit status, all in a single function call.
As a bonus, the debug logging now indicates whether the process
is being run to read from it, feed it data, chat with it (writing and
reading), or just call it for its side effect.
Test suite now passes with -threaded!
I traced back all the hangs with -threaded to System.Cmd.Utils. It seems
it's just crappy/unsafe/outdated, and should not be used. System.Process
seems to be the cool new thing, so converted all the code to use it
instead.
In the process, --debug stopped printing commands it runs. I may try to
bring that back later.
Note that even SafeSystem was switched to use System.Process. Since that
was a modified version of code from System.Cmd.Utils, it needed to be
converted too. I also got rid of nearly all calls to forkProcess,
and all calls to executeFile, which I'm also doubtful about working
well with -threaded.
