[nest-mpi-races] SetKernelStatus without rank guard in test files

[wody34]

📁 Location

• Files: tests/test_nest_file/*.py (6 files)
• Category: nest-mpi-races
• Severity: high
• Hashes: 0d1f9750806d, c15ab18ce2da, 2aa2e840d4bd, bdb5950c5d9b, 9fb87c8a0bf1, 2b4faa1a082c

🔍 Problem

nest.SetKernelStatus() called globally without rank 0 guard. With MPI, ALL ranks execute this, causing race conditions on shared kernel state.

Affected Files

1. spikedetector_mpi_thread.py:14
2. spikegenerator_mpi_dict.py:15
3. step_current_generator_mpi_thread.py:17
4. step_current_generator_mpi.py:14
5. spikegenerator_mpi.py:40
6. spikedetector_mpi.py:14

💡 Fix

# Before
nest.SetKernelStatus({"overwrite_files": True, "total_num_virtual_procs": 4})

# After  
if nest.Rank() == 0:
    nest.SetKernelStatus({"overwrite_files": True, "total_num_virtual_procs": 4})
nest.Barrier()  # Synchronize after kernel modification

🧪 TDD Evidence

Test file: tests/evidence/test_nest_mpi_races.py

• Verifies rank-guarded pattern only allows rank 0 to modify kernel
• Documents current broken pattern lacking guards

tests/evidence/test_nest_mpi_races.py::TestNestMpiRaceConditions::test_set_kernel_status_pattern_with_rank_guard PASSED
tests/evidence/test_nest_mpi_races.py::TestNestMpiRaceConditions::test_current_code_lacks_rank_guard PASSED

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Run: 2026-02-05-1228 | Auto-generated by UltraQA