# Nondeterministic errors in compiled code under macOS **URL:** \ **Category:** Help!\ **Tags:** bug\ **Created:** [May 31, 2020, 8:48am UTC](https://swi-prolog.discourse.group/t/nondeterministic-errors-in-compiled-code-under-macos/2439 "2020-05-31T08:48:31Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Iam](https://avatars.discourse-cdn.com/v4/letter/i/58956e/32.png) [@Iam](https://swi-prolog.discourse.group/u/Iam)\ **Post date:** [May 31, 2020, 8:48am UTC](https://swi-prolog.discourse.group/t/nondeterministic-errors-in-compiled-code-under-macos/2439/1 "2020-05-31T08:48:31Z")
I’m using: SWI-Prolog version 8.1.26 I am compiling the code with \> swipl --goal=main -o tester4 -c tester.pl I want the code to: Behave the same if executed multiple times with exactly the same input data But what I’m getting is: The compiled program sometimes hangs and sometimes (with exactly the same input) does not hang. (I assume it is a memory leak in the generate C-Code.) This error occurred multiple times when using SWI-Prolog version 8.1.26 under macOS version Mojave 10.14.6. But I could not reproduce the error, when using SWI-Prolog version 8.1.26 under Parallels desktop Windows on the same Mac computer, i.e., compiled under Parallels Windows the code produces always the same correct results. My code looks like this: As my code contains the solutions to the assignments for my students, pIease ask for the code via email to [stb@upb.de](mailto:stb@upb.de). ---
**Author:** ![jan](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/jan/32/4_2.png) [@jan](https://swi-prolog.discourse.group/u/jan)\ **Post date:** [May 31, 2020, 9:06am UTC](https://swi-prolog.discourse.group/t/nondeterministic-errors-in-compiled-code-under-macos/2439/2 "2020-05-31T09:06:00Z")
You can send the code in a private message. If it can be reproduced and is still relevant (the last fixup tp 8.3 fixed quite a few issues), it is worth a try. Make sure it is complete though, so I can really run it. ---
**Author:** ![Iam](https://avatars.discourse-cdn.com/v4/letter/i/58956e/32.png) [@Iam](https://swi-prolog.discourse.group/u/Iam)\ **Post date:** [May 31, 2020, 10:02am UTC](https://swi-prolog.discourse.group/t/nondeterministic-errors-in-compiled-code-under-macos/2439/3 "2020-05-31T10:02:11Z")
Hello Jan, thank you for your fast response! Meanwhile, I have also tested the code under opensuse, and I got the same nondeterministic hanging errors as under macOS (which I could not yet reproduce under Parallels Windows). Please find attached the .zip-file including the code and 2 screenshots. Regards, Stefan Böttcher (Attachment Code sometimes hanging under macOS.zip is missing) ---
**Author:** ![Iam](https://avatars.discourse-cdn.com/v4/letter/i/58956e/32.png) [@Iam](https://swi-prolog.discourse.group/u/Iam)\ **Post date:** [May 31, 2020, 10:48am UTC](https://swi-prolog.discourse.group/t/nondeterministic-errors-in-compiled-code-under-macos/2439/6 "2020-05-31T10:48:49Z")
In this thread, I can see everything (including the code that should be kept private). Is this a private channel? Stefan ---
**Author:** ![jan](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/jan/32/4_2.png) [@jan](https://swi-prolog.discourse.group/u/jan)\ **Post date:** [May 31, 2020, 2:53pm UTC](https://swi-prolog.discourse.group/t/nondeterministic-errors-in-compiled-code-under-macos/2439/8 "2020-05-31T14:53:20Z")
> [@Iam](#): > > Meanwhile, I have also tested the code under opensuse, and I got the same nondeterministic hanging errors as under macOS Same under Ubuntu 20.04. Turns out to be a problem with library(time) in terminating the scheduler thread that is used to signal timeouts. I think the same issue may actually cause alarms and call\_with\_time\_limit/2 not to trigger, although I have seen no evidence that this happens. Pushed a fix (for the `clib` submodule). Hope you can deal with just an update to the source? ---
**Author:** ![Iam](https://avatars.discourse-cdn.com/v4/letter/i/58956e/32.png) [@Iam](https://swi-prolog.discourse.group/u/Iam)\ **Post date:** [June 12, 2020, 9:51am UTC](https://swi-prolog.discourse.group/t/nondeterministic-errors-in-compiled-code-under-macos/2439/9 "2020-06-12T09:51:15Z")
Thank you very much for caring about the code and fixing the bugs!