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Fix mpi io data leak - #2114
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thierrydaoud wants to merge 3 commits into
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Fix mpi io data leak#2114thierrydaoud wants to merge 3 commits into
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Each target allocated an interior-sized array for every MPI_IO_DATA%var(i)%sf and then set sf => null(), leaving the array unreachable. The arrays were never used: s_initialize_mpi_data points each sf at the q_cons_vf, beta or pb/mv slices before every MPI-IO read or write, and sf defaults to null(). simulation lost sys_size arrays per rank in every MPI build, plus sys_size + 1 more with Lagrangian bubbles (384 MB and 832 MB per rank for a single-fluid 3D case at 200^3). Measured on 100^3, 1 rank: heap 1,108,359,392 B -> 1,060,286,992 B (6 x 8 MB).
thierrydaoud
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sbryngelson
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October 27, 2026 17:02
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Claude Code Review Head SHA: ecc5f16 The review produced no output (Claude step: failure). Run and transcript: https://github.com/MFlowCode/MFC/actions/runs/40546783749 |
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## master #2114 +/- ##
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- Coverage 62.02% 62.02% -0.01%
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Files 86 86
Lines 22936 22910 -26
Branches 3370 3364 -6
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- Hits 14226 14209 -17
+ Misses 6210 6205 -5
+ Partials 2500 2496 -4 ☔ View full report in Codecov by Harness. 🚀 New features to boost your workflow:
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Description
s_initialize_global_parameters_modulein all three targets allocates an interior-sized array for eachMPI_IO_DATA%var(i)%sfand then immediately doessf => null(). The arrays become unreachable and are never freed. The arrays are also never needed:s_initialize_mpi_data/s_initialize_mpi_data_ds(src/common/m_mpi_common.fpp) point everysfat the existingq_cons_vf,beta,pb/mvslices before each MPI-IO read or write (in post_process throughs_setup_mpi_io_params), andsfalready defaults tonull()inscalar_field.This PR deletes those allocate-then-nullify loops. The
MPI_IO_DATA%var/%viewarrays themselves are still allocated as before.Memory lost per rank before this change, with (m+1)(n+1)(p+1) × 8 bytes per array:
parallel_io)sys_size; withbubbles_lagrange,sys_size+sys_size + 12*nb*nnodesys_size(if notdown_sample)sys_size(larger withdown_sample)Example: 3D, single fluid (
sys_size= 6), 200³ cells per rank: 384 MB of host memory lost per rank, and 832 MB with Lagrangian bubbles. On APUs (MI300A) host and device share the same HBM.Testing
simulationmid-run (macOSheap), 3D single-fluid shock tube, 100³ cells, 1 rank:e95a827a: 1,108,359,392 B./mfc.sh test -j 8, CPU, macOS): 726 passed, 0 failed, 39 skipped