[GitHub] [arrow] pitrou commented on a change in pull request #9280: ARROW-8928: [C++] Add microbenchmarks to help measure ExecBatchIterator overhead

[GitBox <gi...@apache.org>]

pitrou commented on a change in pull request #9280:
URL: https://github.com/apache/arrow/pull/9280#discussion_r562057646



##########
File path: cpp/src/arrow/compute/internals_benchmark.cc
##########
@@ -0,0 +1,86 @@
+// Licensed to the Apache Software Foundation (ASF) under one

Review comment:
       We already have `function_benchmark.cc` for such internals benchmarks.

##########
File path: cpp/src/arrow/compute/internals_benchmark.cc
##########
@@ -0,0 +1,86 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+#include "benchmark/benchmark.h"
+
+#include "arrow/compute/exec_internal.h"
+#include "arrow/testing/gtest_util.h"
+#include "arrow/testing/random.h"
+#include "arrow/util/benchmark_util.h"
+
+namespace arrow {
+namespace compute {
+namespace detail {
+
+constexpr int32_t kSeed = 0xfede4a7e;
+
+void BM_ExecBatchIterator(benchmark::State& state) {
+  // Measure overhead related to deconstructing vector<Datum> into a sequence of ExecBatch
+  random::RandomArrayGenerator rag(kSeed);
+
+  const int64_t length = 1 << 20;
+  const int num_fields = 10;
+
+  std::vector<Datum> args(num_fields);
+  for (int i = 0; i < num_fields; ++i) {
+    args[i] = rag.Int64(length, 0, 100)->data();
+  }
+
+  for (auto _ : state) {
+    std::unique_ptr<ExecBatchIterator> it =
+        *ExecBatchIterator::Make(args, state.range(0));
+    ExecBatch batch;
+    while (it->Next(&batch)) {
+      for (int i = 0; i < num_fields; ++i) {
+        auto data = batch.values[i].array()->buffers[1]->data();
+        benchmark::DoNotOptimize(data);
+      }
+      continue;
+    }
+    benchmark::DoNotOptimize(batch);
+  }
+
+  state.SetItemsProcessed(state.iterations());
+}
+
+void BM_DatumSlice(benchmark::State& state) {
+  // Measure overhead related to deconstructing vector<Datum> into a sequence of ExecBatch
+  random::RandomArrayGenerator rag(kSeed);
+
+  const int64_t length = 1000;
+
+  int num_datums = 1000;
+  std::vector<Datum> datums(num_datums);
+  for (int i = 0; i < num_datums; ++i) {
+    datums[i] = rag.Int64(length, 0, 100)->data();
+  }
+
+  for (auto _ : state) {
+    for (const Datum& datum : datums) {
+      auto slice = datum.array()->Slice(16, 64);

Review comment:
       Is it significantly different from slicing an array? Otherwise, is there a point for the specific "slice a datum" operation?

##########
File path: cpp/src/arrow/compute/internals_benchmark.cc
##########
@@ -0,0 +1,86 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+#include "benchmark/benchmark.h"
+
+#include "arrow/compute/exec_internal.h"
+#include "arrow/testing/gtest_util.h"
+#include "arrow/testing/random.h"
+#include "arrow/util/benchmark_util.h"
+
+namespace arrow {
+namespace compute {
+namespace detail {
+
+constexpr int32_t kSeed = 0xfede4a7e;
+
+void BM_ExecBatchIterator(benchmark::State& state) {
+  // Measure overhead related to deconstructing vector<Datum> into a sequence of ExecBatch
+  random::RandomArrayGenerator rag(kSeed);
+
+  const int64_t length = 1 << 20;
+  const int num_fields = 10;
+
+  std::vector<Datum> args(num_fields);
+  for (int i = 0; i < num_fields; ++i) {
+    args[i] = rag.Int64(length, 0, 100)->data();
+  }
+
+  for (auto _ : state) {
+    std::unique_ptr<ExecBatchIterator> it =
+        *ExecBatchIterator::Make(args, state.range(0));
+    ExecBatch batch;
+    while (it->Next(&batch)) {
+      for (int i = 0; i < num_fields; ++i) {
+        auto data = batch.values[i].array()->buffers[1]->data();
+        benchmark::DoNotOptimize(data);
+      }
+      continue;
+    }
+    benchmark::DoNotOptimize(batch);
+  }
+
+  state.SetItemsProcessed(state.iterations());

Review comment:
       "items" is a bit ambiguous in this benchmark, but I would expect something else than the number of iterations. Perhaps the number of arrays yielded in the inner loop above?

##########
File path: cpp/src/arrow/compute/internals_benchmark.cc
##########
@@ -0,0 +1,86 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+#include "benchmark/benchmark.h"
+
+#include "arrow/compute/exec_internal.h"
+#include "arrow/testing/gtest_util.h"
+#include "arrow/testing/random.h"
+#include "arrow/util/benchmark_util.h"
+
+namespace arrow {
+namespace compute {
+namespace detail {
+
+constexpr int32_t kSeed = 0xfede4a7e;
+
+void BM_ExecBatchIterator(benchmark::State& state) {
+  // Measure overhead related to deconstructing vector<Datum> into a sequence of ExecBatch
+  random::RandomArrayGenerator rag(kSeed);
+
+  const int64_t length = 1 << 20;
+  const int num_fields = 10;
+
+  std::vector<Datum> args(num_fields);
+  for (int i = 0; i < num_fields; ++i) {
+    args[i] = rag.Int64(length, 0, 100)->data();
+  }
+
+  for (auto _ : state) {
+    std::unique_ptr<ExecBatchIterator> it =
+        *ExecBatchIterator::Make(args, state.range(0));
+    ExecBatch batch;
+    while (it->Next(&batch)) {
+      for (int i = 0; i < num_fields; ++i) {
+        auto data = batch.values[i].array()->buffers[1]->data();
+        benchmark::DoNotOptimize(data);
+      }
+      continue;
+    }
+    benchmark::DoNotOptimize(batch);
+  }
+
+  state.SetItemsProcessed(state.iterations());
+}
+
+void BM_DatumSlice(benchmark::State& state) {
+  // Measure overhead related to deconstructing vector<Datum> into a sequence of ExecBatch

Review comment:
       Looks like this was copy-pasted?




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