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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,84 @@ | ||
| /*! | ||
| * Copyright (c) 2021 by Contributors | ||
| * \file parallel_for.h | ||
| * \brief Implemenation of parallel for loop | ||
| * \author Hyunsu Cho | ||
| */ | ||
| #ifndef TREELITE_THREADING_UTILS_PARALLEL_FOR_H_ | ||
| #define TREELITE_THREADING_UTILS_PARALLEL_FOR_H_ | ||
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|
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| #include <treelite/logging.h> | ||
| #include <future> | ||
| #include <thread> | ||
| #include <algorithm> | ||
| #include <vector> | ||
| #include <cstddef> | ||
|
|
||
| namespace treelite { | ||
| namespace threading_utils { | ||
|
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| template <typename IndexType> | ||
| std::vector<IndexType> ComputeWorkRange(IndexType begin, IndexType end, std::size_t nthread); | ||
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| template <typename IndexType, typename FuncType> | ||
| void ParallelFor(IndexType begin, IndexType end, std::size_t nthread, FuncType func) { | ||
| TREELITE_CHECK_GT(nthread, 0) << "nthread must be positive"; | ||
| TREELITE_CHECK_LE(nthread, std::thread::hardware_concurrency()) | ||
| << "nthread cannot exceed " << std::thread::hardware_concurrency(); | ||
| if (begin == end) { | ||
| return; | ||
| } | ||
| /* Divide the range [begin, end) equally among the threads. | ||
| * The i-th thread gets the range [work_range[i], work_range[i+1]). */ | ||
| std::vector<IndexType> work_range = ComputeWorkRange(begin, end, nthread); | ||
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| // Launch (nthread - 1) threads, as the main thread should also perform work. | ||
| std::vector<std::future<void>> async_tasks; | ||
| for (std::size_t thread_id = 1; thread_id < nthread; ++thread_id) { | ||
| async_tasks.push_back(std::async(std::launch::async, [&work_range, &func, thread_id]() { | ||
| const IndexType begin_ = work_range[thread_id]; | ||
| const IndexType end_ = work_range[thread_id + 1]; | ||
| for (IndexType i = begin_; i < end_; ++i) { | ||
| func(i, thread_id); | ||
| } | ||
| })); | ||
| } | ||
| { | ||
| const IndexType begin_ = work_range[0]; | ||
| const IndexType end_ = work_range[1]; | ||
| for (IndexType i = begin_; i < end_; ++i) { | ||
| func(i, 0); | ||
| } | ||
| } | ||
| // Join threads | ||
| for (auto& task : async_tasks) { | ||
| task.get(); | ||
| } | ||
| } | ||
|
|
||
| template <typename IndexType> | ||
| std::vector<IndexType> ComputeWorkRange(IndexType begin, IndexType end, std::size_t nthread) { | ||
| TREELITE_CHECK_GE(end, 0) << "end must be 0 or greater"; | ||
| TREELITE_CHECK_GE(begin, 0) << "begin must be 0 or greater"; | ||
| TREELITE_CHECK_GE(end, begin) << "end cannot be less than begin"; | ||
| TREELITE_CHECK_GT(nthread, 0) << "nthread must be positive"; | ||
| IndexType num_elem = end - begin; | ||
| const IndexType portion = num_elem / nthread + !!(num_elem % nthread); | ||
| // integer division, rounded-up | ||
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| std::vector<IndexType> work_range(nthread + 1); | ||
| work_range[0] = begin; | ||
| IndexType acc = begin; | ||
| for (std::size_t i = 0; i < nthread; ++i) { | ||
| acc += portion; | ||
| work_range[i + 1] = std::min(acc, end); | ||
| } | ||
| TREELITE_CHECK_EQ(work_range[nthread], end); | ||
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| return work_range; | ||
| } | ||
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| } // namespace threading_utils | ||
| } // namespace treelite | ||
|
|
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| #endif // TREELITE_THREADING_UTILS_PARALLEL_FOR_H_ |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,137 @@ | ||
| /*! | ||
| * Copyright (c) 2021 by Contributors | ||
| * \file test_threading_utils.cc | ||
| * \author Hyunsu Cho | ||
| * \brief C++ tests for threading utilities | ||
| */ | ||
| #include <gtest/gtest.h> | ||
| #include <gmock/gmock.h> | ||
| #include <vector> | ||
| #include <algorithm> | ||
| #include <thread> | ||
| #include <random> | ||
| #include <cstddef> | ||
| #include <cstdint> | ||
| #include "threading_utils/parallel_for.h" | ||
|
|
||
| namespace { | ||
|
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||
| class RandomGenerator { | ||
| public: | ||
| RandomGenerator() | ||
| : rng_(std::random_device()()), | ||
| int_dist_(std::numeric_limits<int64_t>::min(), std::numeric_limits<int64_t>::max()), | ||
| real_dist_(0.0, 1.0) {} | ||
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| int64_t DrawInteger(int64_t low, int64_t high) { | ||
| TREELITE_CHECK_LT(low, high); | ||
| int64_t out = int_dist_(rng_); | ||
| int64_t rem = out % (high - low); | ||
| int64_t ret; | ||
| if (rem < 0) { | ||
| ret = high + rem; | ||
| } else { | ||
| ret = low + rem; | ||
| } | ||
| TREELITE_CHECK_GE(ret, low); | ||
| TREELITE_CHECK_LT(ret, high); | ||
| return ret; | ||
| } | ||
|
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| double DrawReal(double low, double high) { | ||
| TREELITE_CHECK_LT(low, high); | ||
| return real_dist_(rng_) * (high - low) + low; | ||
| } | ||
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| private: | ||
| std::mt19937 rng_; | ||
| std::uniform_int_distribution<int64_t> int_dist_; | ||
| std::uniform_real_distribution<double> real_dist_; | ||
| }; | ||
|
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| } // namespace anonymous | ||
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| namespace treelite { | ||
| namespace threading_utils { | ||
|
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| TEST(ThreadingUtils, ComputeWorkRange) { | ||
| /* Test error handling */ | ||
| EXPECT_THROW(ComputeWorkRange(0, 100, 0), treelite::Error); | ||
| EXPECT_THROW(ComputeWorkRange(-100, 100, 3), treelite::Error); | ||
| EXPECT_THROW(ComputeWorkRange(-200, -100, 3), treelite::Error); | ||
| EXPECT_THROW(ComputeWorkRange(200, 100, 3), treelite::Error); | ||
|
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| /* Property-based testing with randomly generated parameters */ | ||
| RandomGenerator rng; | ||
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| constexpr int kNumTrial = 200; | ||
| for (int i = 0; i < kNumTrial; ++i) { | ||
| int64_t begin = rng.DrawInteger(0, 10000); | ||
| std::size_t nthread = static_cast<std::size_t>(rng.DrawInteger(1, 100)); | ||
| int64_t end = rng.DrawInteger(begin, 10000); | ||
| auto range = ComputeWorkRange(begin, end, nthread); | ||
| EXPECT_EQ(range.size(), nthread + 1); | ||
| EXPECT_EQ(range[0], begin); | ||
| EXPECT_EQ(range[nthread], end); | ||
| for (std::size_t i = 0; i < nthread; ++i) { | ||
| EXPECT_GE(range[i + 1], range[i]); | ||
| } | ||
| } | ||
| // Test the case with begin == end | ||
| for (int i = 0; i < 10; ++i) { | ||
| int64_t begin = rng.DrawInteger(0, 10000); | ||
| int64_t end = begin; | ||
| std::size_t nthread = static_cast<std::size_t>(rng.DrawInteger(1, 100)); | ||
| auto range = ComputeWorkRange(begin, end, nthread); | ||
| EXPECT_EQ(range.size(), nthread + 1); | ||
| EXPECT_EQ(range[0], begin); | ||
| EXPECT_EQ(range[nthread], begin); | ||
| for (std::size_t i = 0; i < nthread; ++i) { | ||
| EXPECT_EQ(range[i + 1], range[i]); | ||
| } | ||
| } | ||
| } | ||
|
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| TEST(ThreadingUtils, ParallelFor) { | ||
| /* Test error handling */ | ||
| const int max_thread = std::thread::hardware_concurrency(); | ||
|
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| auto dummy_func = [](int, std::size_t) {}; | ||
| EXPECT_THROW(ParallelFor(0, 100, 0, dummy_func), treelite::Error); | ||
| EXPECT_THROW(ParallelFor(200, 100, 3, dummy_func), treelite::Error); | ||
| EXPECT_THROW(ParallelFor(-100, 100, 3, dummy_func), treelite::Error); | ||
| EXPECT_THROW(ParallelFor(-200, -100, 3, dummy_func), treelite::Error); | ||
| EXPECT_THROW(ParallelFor(200, 100, 3, dummy_func), treelite::Error); | ||
| EXPECT_THROW(ParallelFor(10, 20, 3 * max_thread, dummy_func), treelite::Error); | ||
|
|
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| /* Property-based testing with randomly generated parameters */ | ||
| constexpr int kVectorLength = 10000; | ||
| RandomGenerator rng; | ||
| std::vector<double> a(kVectorLength); | ||
| std::vector<double> b(kVectorLength); | ||
| std::generate_n(a.begin(), kVectorLength, [&rng]() { return rng.DrawReal(-1.0, 1.0); }); | ||
| std::generate_n(b.begin(), kVectorLength, [&rng]() { return rng.DrawReal(-10.0, 10.0); }); | ||
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| constexpr int kNumTrial = 200; | ||
| for (int i = 0; i < kNumTrial; ++i) { | ||
| std::vector<double> c(kVectorLength); | ||
| // Fill c with dummy values | ||
| std::generate_n(c.begin(), kVectorLength, [&rng]() { return rng.DrawReal(100.0, 200.0); }); | ||
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| // Compute c := a + b on range [begin, end) | ||
| int64_t begin = rng.DrawInteger(0, kVectorLength); | ||
| std::size_t nthread = static_cast<std::size_t>(rng.DrawInteger(1, max_thread + 1)); | ||
| int64_t end = rng.DrawInteger(begin, kVectorLength); | ||
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| ParallelFor(begin, end, nthread, [&a, &b, &c](int64_t i, std::size_t) { | ||
| c[i] = a[i] + b[i]; | ||
| }); | ||
|
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| for (int64_t i = begin; i < end; ++i) { | ||
| EXPECT_FLOAT_EQ(c[i], a[i] + b[i]) << ", at index " << i; | ||
| } | ||
| } | ||
| } | ||
|
|
||
| } // namespace threading_utils | ||
| } // namespace treelite |
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