segfault in ABM with OpenMP

[dabele]

Bug description

OpenMP multithreaded abm_simulation crashes with a segfault. without OpenMP (or OMP_NUM_THREADS=1) the program runs normal. In Release build the crash happened reliably for me. In Debug builds the crash doesn't always happen or takes a long time to happen, so it's hard to debug

Version

Linux

To reproduce

1. build abm_simulation with MEMILIO_ENABLE_OPENMP=ON
2. export OMP_NUM_THREADS=<N>, higher N seems to increase chance of it happening.
3. run abm_simulation 1 <dir>

Relevant log output

No response

Add any relevant information, e.g. used compiler, screenshots.

gcc 11, ubuntu 20

Checklist

• Attached labels, especially loc:: or model:: labels.
• Linked to project

[dabele]

Should probably prioritize adding unit tests with OpenMP: #786

[dabele]

Actually I found the error, it's the unordered_map in TestingStrategy::m_location_to_schemes_map. The lookup with unordered_map::operator[] in TestingStrategy::run_strategy is not thread safe. That should be resolved with #830. Keep the issue open for now, retest when #830 is merged.

[mknaranja]

@charlie0614 Was this maybe the problem you were facing?

[xsaschako]

@charlie0614 Was this maybe the problem you were facing?

Yes, it was. I hadn't known about it either, so after we found what the issue was, Daniel showed us his resolution.
Also, for us it was happening only with scorep, not in gcc.