make PrestoSerializer compression compatible with Presto and add stats (

facebookincubator#8851)

Summary:
Presto uses the uncompressed size as part of checksum, not the compressed size. Presto also does not use the compression result unless it is under 0,8 x the source size. Presto does not require the compressed bit to be set if a compressing exchange codec is in place.

Adds counters to serializers for tracking compression efficacity.

Adds a setting to OutputBufferManager to decide if compression should be attempted for exchange.

Compatibly with Presto, uses uncompressed output if compression yields less then 20% savings. In addition to Presto, skips attempting compression for a number of forthcoming batches if compression was not effective.

Reports the compression input bytes, compressed bytes and bytes for which compression was not attempted in runtimeStats.

Pull Request resolved: facebookincubator#8851

Reviewed By: xiaoxmeng

Differential Revision: D54178975

Pulled By: oerling

fbshipit-source-id: 389d7c0d1f9590468c91a405c5c5e5834d29c0da

velox/exec/Exchange.cpp

@@ -123,7 +123,7 @@ RowVectorPtr Exchange::getOutput() {
 
     while (!inputStream.atEnd()) {
       getSerde()->deserialize(
-          &inputStream, pool(), outputType_, &result_, resultOffset);
+          &inputStream, pool(), outputType_, &result_, resultOffset, &options_);
       resultOffset = result_->size();
     }
   }

velox/exec/Exchange.h

@@ -19,6 +19,8 @@
 #include <random>
 #include "velox/exec/ExchangeClient.h"
 #include "velox/exec/Operator.h"
+#include "velox/exec/OutputBufferManager.h"
+#include "velox/serializers/PrestoSerializer.h"
 
 namespace facebook::velox::exec {
 
@@ -50,7 +52,10 @@ class Exchange : public SourceOperator {
         preferredOutputBatchBytes_{
             driverCtx->queryConfig().preferredOutputBatchBytes()},
         processSplits_{operatorCtx_->driverCtx()->driverId == 0},
-        exchangeClient_{std::move(exchangeClient)} {}
+        exchangeClient_{std::move(exchangeClient)} {
+    options_.compressionKind =
+        OutputBufferManager::getInstance().lock()->compressionKind();
+  }
 
   ~Exchange() override {
     close();
@@ -105,6 +110,7 @@ class Exchange : public SourceOperator {
   std::vector<std::unique_ptr<SerializedPage>> currentPages_;
   bool atEnd_{false};
   std::default_random_engine rng_{std::random_device{}()};
+  serializer::presto::PrestoVectorSerde::PrestoOptions options_;
 };
 
 } // namespace facebook::velox::exec

velox/exec/OutputBufferManager.cpp

@@ -17,11 +17,21 @@
 #include "velox/exec/Task.h"
 
 namespace facebook::velox::exec {
+// static
+void OutputBufferManager::initialize(const Options& options) {
+  std::lock_guard<std::mutex> l(initMutex_);
+  VELOX_CHECK(
+      instance_ == nullptr, "May initialize OutputBufferManager only once");
+  instance_ = std::make_shared<OutputBufferManager>(options);
+}
 
 // static
 std::weak_ptr<OutputBufferManager> OutputBufferManager::getInstance() {
-  static auto kInstance = std::make_shared<OutputBufferManager>();
-  return kInstance;
+  std::lock_guard<std::mutex> l(initMutex_);
+  if (!instance_) {
+    instance_ = std::make_shared<OutputBufferManager>(Options());
+  }
+  return instance_;
 }
 
 std::shared_ptr<OutputBuffer> OutputBufferManager::getBuffer(

velox/exec/OutputBufferManager.h

@@ -21,6 +21,18 @@ namespace facebook::velox::exec {
 
 class OutputBufferManager {
  public:
+  /// Options for shuffle. This is initialized once and affects both
+  /// PartitionedOutput and Exchange. This can be used for controlling
+  /// compression, protocol version and other matters where shuffle sides should
+  /// agree.
+  struct Options {
+    common::CompressionKind compressionKind{
+        common::CompressionKind::CompressionKind_NONE};
+  };
+
+  OutputBufferManager(Options options)
+      : compressionKind_(options.compressionKind) {}
+
   void initializeTask(
       std::shared_ptr<Task> task,
       core::PartitionedOutputNode::Kind kind,
@@ -84,6 +96,10 @@ class OutputBufferManager {
 
   void removeTask(const std::string& taskId);
 
+  /// Initializes singleton with 'options'. May be called once before
+  /// getInstance().
+  static void initialize(const Options& options);
+
   static std::weak_ptr<OutputBufferManager> getInstance();
 
   uint64_t numBuffers() const;
@@ -117,17 +133,30 @@ class OutputBufferManager {
   // Returns NULL if task not found.
   std::shared_ptr<OutputBuffer> getBufferIfExists(const std::string& taskId);
 
+  void testingSetCompression(common::CompressionKind kind) {
+    *const_cast<common::CompressionKind*>(&compressionKind_) = kind;
+  }
+
+  common::CompressionKind compressionKind() const {
+    return compressionKind_;
+  }
+
  private:
   // Retrieves the set of buffers for a query.
   // Throws an exception if buffer doesn't exist.
   std::shared_ptr<OutputBuffer> getBuffer(const std::string& taskId);
 
+  const common::CompressionKind compressionKind_;
+
   folly::Synchronized<
       std::unordered_map<std::string, std::shared_ptr<OutputBuffer>>,
       std::mutex>
       buffers_;
 
   std::function<std::unique_ptr<OutputStreamListener>()> listenerFactory_{
       nullptr};
+
+  inline static std::shared_ptr<OutputBufferManager> instance_;
+  inline static std::mutex initMutex_;
 };
 } // namespace facebook::velox::exec

velox/exec/PartitionedOutput.cpp

@@ -19,7 +19,6 @@
 #include "velox/exec/Task.h"
 
 namespace facebook::velox::exec {
-
 namespace detail {
 BlockingReason Destination::advance(
     uint64_t maxBytes,
@@ -55,7 +54,11 @@ BlockingReason Destination::advance(
   if (!current_) {
     current_ = std::make_unique<VectorStreamGroup>(pool_);
     auto rowType = asRowType(output->type());
-    current_->createStreamTree(rowType, rowsInCurrent_);
+    serializer::presto::PrestoVectorSerde::PrestoOptions options;
+    options.compressionKind =
+        OutputBufferManager::getInstance().lock()->compressionKind();
+    options.minCompressionRatio = PartitionedOutput::minCompressionRatio();
+    current_->createStreamTree(rowType, rowsInCurrent_, &options);
   }
   current_->append(
       output, folly::Range(&rows_[firstRow], rowIdx_ - firstRow), scratch);
@@ -107,6 +110,18 @@ BlockingReason Destination::flush(
   return blocked ? BlockingReason::kWaitForConsumer
                  : BlockingReason::kNotBlocked;
 }
+
+void Destination::updateStats(Operator* op) {
+  VELOX_CHECK(finished_);
+  if (current_) {
+    const auto serializerStats = current_->runtimeStats();
+    auto lockedStats = op->stats().wlock();
+    for (auto& pair : serializerStats) {
+      lockedStats->addRuntimeStat(pair.first, pair.second);
+    }
+  }
+}
+
 } // namespace detail
 
 PartitionedOutput::PartitionedOutput(
@@ -366,6 +381,7 @@ RowVectorPtr PartitionedOutput::getOutput() {
       }
       destination->flush(*bufferManager, bufferReleaseFn_, nullptr);
       destination->setFinished();
+      destination->updateStats(this);
     }
 
     bufferManager->noMoreData(operatorCtx_->task()->taskId());

velox/exec/PartitionedOutput.h

@@ -85,6 +85,9 @@ class Destination {
     return bytesInCurrent_;
   }
 
+  /// Adds stats from 'this' to runtime stats of 'op'.
+  void updateStats(Operator* op);
+
  private:
   // Sets the next target size for flushing. This is called at the
   // start of each batch of output for the destination. The effect is
@@ -182,6 +185,14 @@ class PartitionedOutput : public Operator {
     destinations_.clear();
   }
 
+  static void testingSetMinCompressionRatio(float ratio) {
+    minCompressionRatio_ = ratio;
+  }
+
+  static float minCompressionRatio() {
+    return minCompressionRatio_;
+  }
+
  private:
   void initializeInput(RowVectorPtr input);
 
@@ -194,6 +205,10 @@ class PartitionedOutput : public Operator {
   /// Collect all rows with null keys into nullRows_.
   void collectNullRows();
 
+  // If compression in serde is enabled, this is the minimum compression that
+  // must be achieved before starting to skip compression. Used for testing.
+  inline static float minCompressionRatio_ = 0.8;
+
   const std::vector<column_index_t> keyChannels_;
   const int numDestinations_;
   const bool replicateNullsAndAny_;

velox/exec/tests/MultiFragmentTest.cpp

@@ -22,6 +22,7 @@
 #include "velox/dwio/common/tests/utils/BatchMaker.h"
 #include "velox/exec/Exchange.h"
 #include "velox/exec/OutputBufferManager.h"
+#include "velox/exec/PartitionedOutput.h"
 #include "velox/exec/PlanNodeStats.h"
 #include "velox/exec/RoundRobinPartitionFunction.h"
 #include "velox/exec/tests/utils/AssertQueryBuilder.h"
@@ -2000,5 +2001,61 @@ TEST_F(MultiFragmentTest, mergeSmallBatchesInExchange) {
   test(100'000, 1);
 }
 
+TEST_F(MultiFragmentTest, compression) {
+  bufferManager_->testingSetCompression(
+      common::CompressionKind::CompressionKind_LZ4);
+  auto guard = folly::makeGuard([&]() {
+    bufferManager_->testingSetCompression(
+        common::CompressionKind::CompressionKind_NONE);
+  });
+
+  constexpr int32_t kNumRepeats = 1'000'000;
+  const auto data = makeRowVector({makeFlatVector<int64_t>({1, 2, 3})});
+
+  const auto producerPlan = test::PlanBuilder()
+                                .values({data}, false, kNumRepeats)
+                                .partitionedOutput({}, 1)
+                                .planNode();
+  const auto producerTaskId = "local://t1";
+
+  const auto plan = test::PlanBuilder()
+                        .exchange(asRowType(data->type()))
+                        .singleAggregation({}, {"sum(c0)"})
+                        .planNode();
+
+  const auto expected =
+      makeRowVector({makeFlatVector<int64_t>(std::vector<int64_t>{6000000})});
+
+  const auto test = [&](float minCompressionRatio, bool expectSkipCompression) {
+    PartitionedOutput::testingSetMinCompressionRatio(minCompressionRatio);
+    auto producerTask = makeTask(producerTaskId, producerPlan);
+    producerTask->start(1);
+
+    auto consumerTask = test::AssertQueryBuilder(plan)
+                            .split(remoteSplit(producerTaskId))
+                            .destination(0)
+                            .assertResults(expected);
+
+    auto consumerTaskStats = exec::toPlanStats(consumerTask->taskStats());
+    const auto& consumerPlanStats = consumerTaskStats.at("0");
+    ASSERT_EQ(data->size() * kNumRepeats, consumerPlanStats.outputRows);
+
+    auto producerTaskStats = exec::toPlanStats(producerTask->taskStats());
+    const auto& producerStats = producerTaskStats.at("1");
+    // The data is extremely compressible, 1, 2, 3 repeated 1000000 times.
+    if (!expectSkipCompression) {
+      EXPECT_LT(
+          producerStats.customStats.at("compressedBytes").sum,
+          producerStats.customStats.at("compressionInputBytes").sum);
+      EXPECT_EQ(0, producerStats.customStats.at("compressionSkippedBytes").sum);
+    } else {
+      EXPECT_LT(0, producerStats.customStats.at("compressionSkippedBytes").sum);
+    }
+  };
+
+  test(0.7, false);
+  test(0.0000001, true);
+}
+
 } // namespace
 } // namespace facebook::velox::exec