Both this (with Posix.Process open):
case fork() of
NONE => (exece(proc,proc::args,env')
handle _ => die ("Exece of "^proc^" failed"))
| SOME cpid => let
val (_, result) = waitpid(W_CHILD cpid, [])
in
result
end
and this:
case fork() of
NONE =>
let
val () = dup2 {old = outoutfd, new = Posix.FileSys.stdout}
val () = dup2 {old = erroutfd, new = Posix.FileSys.stderr}
val () = dup2 {old = ininfd, new = Posix.FileSys.stdin}
val () =
List.app close [errinfd, erroutfd, outinfd, outoutfd,
ininfd, inoutfd]
in
exece(executable,nm_args,env)
end
| SOME pid =>
let
val out = mkTIO_instream outinfd
val err = mkTIO_instream errinfd
val () = List.app close [outoutfd, erroutfd, ininfd, inoutfd]
in
…
end
seem to be causing us grief, particularly on a recent Linux, PolyML 5.7 and
under conditions of some memory load.
The Linux is:
Linux gemma 4.9.1-gnu-1 #1 SMP PREEMPT Sun Jan 8 16:17:57 UYT 2017 x86_64
GNU/Linux
When strace-d, we get a lot of futex calls and interruptions from SIGCHLD.
This is with --gcthreads=1, but pages like
http://www.linuxprogrammingblog.com/threads-and-fork-think-twice-before-using-them
make me a bit nervous about how we might be falling prey to horrible problems.
Is there a better idiom we might use?
Thanks,
Michael
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