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Fix OpenMP thread allocation in Linux #5551

Merged
merged 15 commits into from
Nov 29, 2022
Merged

Fix OpenMP thread allocation in Linux #5551

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0579b56
Fix OpenMP thread allocation in Linux
svotaw Oct 19, 2022
8adfab2
move constant out of ifdef
svotaw Oct 20, 2022
c478523
edit comments
svotaw Oct 20, 2022
c82f5f9
switch to OMP_GET_STREAMING_MAX_THREADS
svotaw Nov 13, 2022
ef7bade
switch to using InitStreaming param
svotaw Nov 13, 2022
5f793bd
fix comment
svotaw Nov 13, 2022
1b94aad
style fix
svotaw Nov 14, 2022
b812cb0
default to -1
svotaw Nov 20, 2022
3c9375d
style fix
svotaw Nov 20, 2022
ff33af5
style fix
svotaw Nov 20, 2022
4b0e07f
adjust initialization
svotaw Nov 20, 2022
9f1ce3c
Merge branch 'master' into omp-thread-fix
svotaw Nov 21, 2022
28098e6
comment edit
svotaw Nov 21, 2022
ab67eef
fix test
svotaw Nov 22, 2022
d87f590
Merge remote-tracking branch 'origin/master' into omp-thread-fix
shiyu1994 Nov 27, 2022
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4 changes: 4 additions & 0 deletions include/LightGBM/utils/openmp_wrapper.h
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,10 @@
#ifndef LIGHTGBM_OPENMP_WRAPPER_H_
#define LIGHTGBM_OPENMP_WRAPPER_H_

/** In an external multi-threaded environment, the below methods can return different values on
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different threads (in Linux at least). To share allocations between threads, use a constant. **/
#define MAX_THREAD_ALLOCATION 128

#ifdef _OPENMP

#include <LightGBM/utils/log.h>
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6 changes: 2 additions & 4 deletions src/c_api.cpp
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Expand Up @@ -1073,7 +1073,6 @@ int LGBM_DatasetPushRowsWithMetadata(DatasetHandle dataset,
if (!data) {
Log::Fatal("data cannot be null.");
}
const int num_omp_threads = OMP_NUM_THREADS();
auto p_dataset = reinterpret_cast<Dataset*>(dataset);
auto get_row_fun = RowFunctionFromDenseMatric(data, nrow, ncol, data_type, 1);
if (p_dataset->has_raw()) {
Expand All @@ -1085,7 +1084,7 @@ int LGBM_DatasetPushRowsWithMetadata(DatasetHandle dataset,
for (int i = 0; i < nrow; ++i) {
OMP_LOOP_EX_BEGIN();
// convert internal thread id to be unique based on external thread id
const int internal_tid = omp_get_thread_num() + (num_omp_threads * tid);
const int internal_tid = omp_get_thread_num() + (MAX_THREAD_ALLOCATION * tid);
auto one_row = get_row_fun(i);
p_dataset->PushOneRow(internal_tid, start_row + i, one_row);
OMP_LOOP_EX_END();
Expand Down Expand Up @@ -1154,7 +1153,6 @@ int LGBM_DatasetPushRowsByCSRWithMetadata(DatasetHandle dataset,
if (!data) {
Log::Fatal("data cannot be null.");
}
const int num_omp_threads = OMP_NUM_THREADS();
auto p_dataset = reinterpret_cast<Dataset*>(dataset);
auto get_row_fun = RowFunctionFromCSR<int>(indptr, indptr_type, indices, data, data_type, nindptr, nelem);
int32_t nrow = static_cast<int32_t>(nindptr - 1);
Expand All @@ -1166,7 +1164,7 @@ int LGBM_DatasetPushRowsByCSRWithMetadata(DatasetHandle dataset,
for (int i = 0; i < nrow; ++i) {
OMP_LOOP_EX_BEGIN();
// convert internal thread id to be unique based on external thread id
const int internal_tid = omp_get_thread_num() + (num_omp_threads * tid);
const int internal_tid = omp_get_thread_num() + (MAX_THREAD_ALLOCATION * tid);
auto one_row = get_row_fun(i);
p_dataset->PushOneRow(internal_tid, static_cast<data_size_t>(start_row + i), one_row);
OMP_LOOP_EX_END();
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6 changes: 3 additions & 3 deletions src/io/sparse_bin.hpp
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Expand Up @@ -82,9 +82,9 @@ class SparseBin : public Bin {
~SparseBin() {}

void InitStreaming(uint32_t num_thread) override {
// Each thread needs its own push buffer, so allocate external num_thread times the number of OMP threads
int num_omp_threads = OMP_NUM_THREADS();
push_buffers_.resize(num_omp_threads * num_thread);
// Each external thread needs its own set of OpenMP push buffers,
// so allocate num_thread times the maximum number of OMP threads per external thread
push_buffers_.resize(MAX_THREAD_ALLOCATION * num_thread);
};

void ReSize(data_size_t num_data) override { num_data_ = num_data; }
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