Hi,

I've noticed some strange behavior of PolyML 4.2.0 for i386/Linux with respect to signals and signal handlers.

Basically, what happens is that after installing my own signal handler for (in my case) the ALRM signal, committing the database, and restarting PolyML, further signals are apparently not delivered anymore, even though the handler itself is installed properly.

Can anyone confirm this behavior, or even better yet, does anyone have an explanation? Maybe I'm just overlooking the obvious.

Below is a minimal example, with relevant output included.

Best regards, Tjark

,----- $./poly Poly/ML RTS version I386-4.1.3 (13:57:33 Sep 30 2002) Copyright (c) 2002 CUTS and contributors. Running with heap parameters (h=10240K,ib=2048K,ip=100%,mb=6144K,mp=20%) Mapping ./ML_dbase Poly/ML 4.1.3 Release

val flag = ref false;

val flag = ref false : bool ref

Signal.signal (Posix.Signal.alrm, Signal.SIG_HANDLE (fn _ => flag := true));

val it = SIG_DFL : Signal.sig_handle

Posix.Process.alarm (Time.fromSeconds 0);

val it = 0.000 : Time.time

!flag;

val it = true : bool

PolyML.commit();

[...] Mapping ./ML_dbase val it = true : bool

PolyML.quit();

$ ./poly Poly/ML RTS version I386-4.1.3 (13:57:33 Sep 30 2002) Copyright (c) 2002 CUTS and contributors. Running with heap parameters (h=10240K,ib=2048K,ip=100%,mb=6144K,mp=20%) Mapping ./ML_dbase Poly/ML 4.1.3 Release

flag := false;

val it = () : unit

Posix.Process.alarm (Time.fromSeconds 0);

val it = 0.000 : Time.time

!flag;

val it = false : bool

So the handler appears not to be called. It is however installed properly:

val (Signal.SIG_HANDLE handler) = Signal.signal (Posix.Signal.alrm,

Signal.SIG_DFL); val handler = fn : int -> unit

handler 14;

val it = () : unit

!flag;

val it = true : bool `-----