Application (Octotiger) gets stuck on hpx::finalize when only using one thread

[G-071]

Expected Behavior

I am currently trying to move the changes I made in Octotiger to the master branch. Therefore I am moving away from HPX 1.0.0 to a more recent version. Expected behaviour: hpx::finalize still works as before for one or more threads.

Actual Behavior

Octotiger (current master branch) itself compiles with a recent(ish) commit of HPX and also works as intended - unless I only uses a single thread. In this case Octotiger still produces the the right result but gets stuck on hpx::finalize. This problem did not occur with HPX 1.0.0.

See inital issue: STEllAR-GROUP/octotiger#61

Steps to Reproduce the Problem

1. Run octotiger -t1 -Problem=moving_star -Max_level=3 -Odt=0.3 -Stoptime=0.2 -Xscale=20.0 -Omega=0.1 -Stopstep=9 -Disableoutput

Specifications

• HPX Version: 29da281
• Octotiger Version: STEllAR-GROUP/octotiger@afef65c
• Vc Version: STEllAR-GROUP/Vc@157026d
• gcc 5.4.0, boost 1.63

[msimberg]

@G-071 There was a problem like this earlier which should already be fixed in master. Could you try again with 0867f8a or newer (i.e. anything after #3110 was merged)?

[G-071]

By now, I have a workaround for STEllAR-GROUP/octotiger#60 so I rebuilt everything with the current HPX master ( ef7360b ) - The problem still persists!

[msimberg]

@G-071 Thanks for testing. Seeing as you already had the problem with c9f2c09 it is most certainly not what I suspected, as you've just confirmed as well.

I will try to get octotiger running to reproduce the problem. I assume you're on Linux? Does debug or release make a difference?

[msimberg]

Would you mind trying to run with a different scheduler? Most probably you want to try local-priority-fifo or abp-priority. I was able to get octotiger to finish with those schedulers, and it consistently hangs with local-priority-lifo. Are you actually able to run octotiger successfully with HPX 1.0, one thread and local-priority-lifo?

I think I know what's causing the lifo scheduler to hang and I'll try to get a fix done for 1.1.

[msimberg]

There is now #3172 which should fix local-priority-lifo.

[G-071]

I just tested your branch in #3172. Octotiger no longer gets stuck upon hpx::finalize when using it with:

octotiger -t1 -Problem=moving_star -Max_level=3 -Odt=0.3 -Stoptime=0.2 -Xscale=20.0 -Omega=0.1 -Stopstep=9 -Disableoutput

This seems to have fixed the issue!

[msimberg]

Good to hear!