Hi, I agree with Frank. There is an alternative function (which uses the same underlying mechanism) -- IO_CallWithTimeout (and IO_CallWithTimeoutList, which just takes the function arguments as a list).
IO_CallWithTimeout(rec(seconds := 2), Intersection, AlternatingGroup(20), AlternatingGroup(20)*(1,2)); (note that IO_CallWithTimeout uses different names for the times, seconds in this case). After about 2 seconds outputs [ false ] Chris -----Original Message----- From: Frank Lübeck <frank.lueb...@math.rwth-aachen.de> Sent: 27 January 2021 18:19 To: Carl-Fredrik Nyberg Brodda (MTH - Postgraduate Researcher) <c.nyberg-bro...@uea.ac.uk> Cc: forum@gap-system.org Subject: Re: [GAP Forum] Run GAP command for x seconds On Wed, Jan 27, 2021 at 04:54:03PM +0000, Carl-Fredrik Nyberg Brodda (MTH - Postgraduate Researcher) wrote: > Thank you for your response. I am having trouble getting the timeout > to work. Do you have an example of using the timeout? > > I have attempted to pass the last (third, optional) argument of > ParTakeFirstResultByFork as rec(TimeOut := rec(tv_sec :=2, tv_usec := > 0)), hoping for my execution to run for 2 seconds, but this does not > work (it never times out). I have also tried setting the tv_sec record > to be the current time (plus 10 seconds or so), but this does not time out > either. Hi, This looks correct and it works for me, for example: gap> Runtimes(); ParTakeFirstResultByFork([function(x) while true do gap> od; end], [[1]],rec(TimeOut := rec(tv_sec :=2, tv_usec := 0 ))); gap> Runtimes(); rec( system_time := 90, system_time_children := 15, user_time := 1103, user_time_children := 3985 ) [ ] rec( system_time := 94, system_time_children := 15, user_time := 1103, user_time_children := 5984 ) I'm only using Linux systems. Some functions of the IO package may not work as expected when GAP is used in Windows (but I don't know the details). Best regards again, Frank Lübeck > Best, > Carl-Fredrik Nyberg Brodda > ________________________________ > From: Frank Lübeck <frank.lueb...@math.rwth-aachen.de> > Sent: Wednesday, January 27, 2021 3:53 PM > To: Carl-Fredrik Nyberg Brodda (MTH - Postgraduate Researcher) > <c.nyberg-bro...@uea.ac.uk> > Cc: forum@gap-system.org <forum@gap-system.org> > Subject: Re: [GAP Forum] Run GAP command for x seconds > > On Wed, Jan 27, 2021 at 02:53:14PM +0000, Carl-Fredrik Nyberg Brodda (MTH - > Postgraduate Researcher) wrote: > > Hi all, > > > > A problem which I recently stumbled upon is the following: is there > > a way to execute a given GAP command only for a certain amount of > > time, before stepping past the command and continuing execution? > > > > Let us say I have a table of finitely many finitely presented > > groups, and wish to see whether GAP has a "naive" solution for their > > word problem. I find a KnuthBendixRewritingSystem() of the group, > > and then run > > MakeConfluent() on this rewriting system. Of course, this process > > may not terminate at all! But sometimes it does. My problem is > > essentially that I wish to run MakeConfluent() for some amount of > > time (say 5 seconds), and then, if the command has not terminated, > > continue on with the next group. This avoids all decidability > > issues, and would in other programming languages be easily implemented with > > a timer. > > > > Of course the problem is general, so the above is just a use-case. > > Is there something that can help with this? > > > > Best, > > Carl-Fredrik Nyberg Brodda > > Dear Forum, > > I have used successfully the function > ParTakeFirstResultByFork > from the IO package for this kind of applications. > It has an optional third argument which allows to specify a timeout. > > Best regards, > Frank -- /// Dr. Frank Lübeck, Lehrstuhl für Algebra und Zahlentheorie, \\\ Pontdriesch 14/16, 52062 Aachen, Germany /// E-mail: frank.lueb...@math.rwth-aachen.de \\\ WWW: http://www.math.rwth-aachen.de/~Frank.Luebeck/ _______________________________________________ Forum mailing list Forum@gap-system.org https://mail.gap-system.org/mailman/listinfo/forum _______________________________________________ Forum mailing list Forum@gap-system.org https://mail.gap-system.org/mailman/listinfo/forum
