Swipl process runs forever at 100% CPU on macOS

I’m using: SWI-Prolog version 8.0.2, installed onto macOS by MacPorts, and the Prolog Development Tools plugin for the Eclipse development environment.

I expect the swipl process to be dormant when I’m not using it.

But I find that when I start up Eclipse, a process starts running at 100% CPU, apparently forever. The process name is swipl. It continues even when I quit Eclipse. When I look at the files being used by that process, I see /opt/local/lib/swipl/boot/history.pl mentioned from time to time.

What is this process trying to do? How can I stop it from consuming 100% CPU forever? If there’s a way to help it achieve what it’s trying to do, so that it can rest, I’ll do that. Right now my workaround is to force-quit that process from the Activity Monitor, but that seems crude.

More details on my environment: macOS 10.13.6 High Sierra, SWI Prolog installed as port swi-prolog @8.0.2_1 by MacPorts, Eclipse installed as LiClipse (liclipse .com) 6.1.0 (recent) on an Eclipse (eclipse .org) 4.1.0 platform, Prolog Development Tools version 3.1.2.

I have noticed this problem on past versions of swi-prolog via MacPorts, and of Prolog Development Tools in the past few years, but this is the first time I’ve posted here about the problem.

Letting the process run for a few hours does not result it eventually finishing. I haven’t had the patience to let it go more than 10 hours or so.

I was hoping that someone who used the same environment as you would respond. I don’t, but I do use the bundled MacOs application (Qt console) and occasionally the command line version and I’ve never observed what you’re seeing. history.pl is concerned with the query history for the top level, so my suspicion is that it has something to do with Prolog Development Tools. Have you asked this question to their support group?

Thank you for the reply. Asking the PDT support list is the next step. Thank you.