[native] Init system used memory cache at the beginning of PeriodicMemoryChecker callback

presto-native-execution/presto_cpp/main/LinuxMemoryChecker.cpp

@@ -62,10 +62,6 @@ class LinuxMemoryChecker : public PeriodicMemoryChecker {
 
   ~LinuxMemoryChecker() override {}
 
-  int64_t getUsedMemory() {
-    return systemUsedMemoryBytes();
-  }
-
   void setStatFile(std::string statFile) {
     memStatFile_ = statFile;
     LOG(INFO) << fmt::format(
@@ -180,7 +176,7 @@ class LinuxMemoryChecker : public PeriodicMemoryChecker {
   // value. It may be better than what we currently use. For
   // consistency we will match cgroup V1 and change if
   // necessary.
-  int64_t systemUsedMemoryBytes() override {
+  void loadSystemMemoryUsage() override {
     size_t memAvailable = 0;
     size_t memTotal = 0;
     size_t inactiveAnon = 0;
@@ -207,7 +203,6 @@ class LinuxMemoryChecker : public PeriodicMemoryChecker {
       // Unit is in bytes.
       const auto memBytes = inactiveAnon + activeAnon;
       cachedSystemUsedMemoryBytes_ = memBytes;
-      return memBytes;
     }
 
     // Last resort use host machine info.
@@ -231,7 +226,6 @@ class LinuxMemoryChecker : public PeriodicMemoryChecker {
     const auto memBytes =
         (memAvailable && memTotal) ? memTotal - memAvailable : 0;
     cachedSystemUsedMemoryBytes_ = memBytes;
-    return memBytes;
   }
 
   int64_t mallocBytes() const override {

presto-native-execution/presto_cpp/main/PeriodicMemoryChecker.cpp

@@ -71,6 +71,7 @@ void PeriodicMemoryChecker::start() {
   scheduler_->setThreadName("MemoryCheckerThread");
   scheduler_->addFunction(
       [&]() {
+        loadSystemMemoryUsage();
         periodicCb();
         if (config_.mallocMemHeapDumpEnabled) {
           maybeDumpHeap();
@@ -92,6 +93,13 @@ void PeriodicMemoryChecker::stop() {
   scheduler_.reset();
 }
 
+int64_t PeriodicMemoryChecker::systemUsedMemoryBytes(bool fetchFresh) {
+  if (fetchFresh) {
+    loadSystemMemoryUsage();
+  }
+  return cachedSystemUsedMemoryBytes_;
+}
+
 std::string PeriodicMemoryChecker::createHeapDumpFilePath() const {
   const size_t now = velox::getCurrentTimeMs() / 1000;
   // Format as follow:
@@ -210,7 +218,9 @@ void PeriodicMemoryChecker::pushbackMemory() {
   RECORD_HISTOGRAM_METRIC_VALUE(
       kCounterMemoryPushbackLatencyMs, latencyUs / 1000);
   const auto actualFreedBytes = std::max<int64_t>(
-      0, static_cast<int64_t>(currentMemBytes) - systemUsedMemoryBytes());
+      0,
+      static_cast<int64_t>(currentMemBytes) -
+          systemUsedMemoryBytes(/*fetchFresh=*/true));
   RECORD_HISTOGRAM_METRIC_VALUE(
       kCounterMemoryPushbackExpectedReductionBytes, freedBytes);
   RECORD_HISTOGRAM_METRIC_VALUE(

presto-native-execution/presto_cpp/main/PeriodicMemoryChecker.h

@@ -76,15 +76,14 @@ class PeriodicMemoryChecker {
   /// Stops the 'PeriodicMemoryChecker'.
   virtual void stop();
 
-  /// Returns the last known cached 'current' system memory usage in bytes.
-  int64_t cachedSystemUsedMemoryBytes() const {
-    return cachedSystemUsedMemoryBytes_;
-  }
+  /// Returns the last known cached 'current' system memory usage in bytes.  If
+  /// 'fetchFresh' is true, retrieves and returns the current system memory usage.
+  /// The returned value is used to compare with 'Config::systemMemLimitBytes'.
+  int64_t systemUsedMemoryBytes(bool fetchFresh = false);
 
  protected:
-  /// Fetches and returns current system memory usage in bytes.
-  /// The returned value is used to compare with 'Config::systemMemLimitBytes'.
-  virtual int64_t systemUsedMemoryBytes() = 0;
+  /// Fetches current system memory usage in bytes and stores it in the cache.
+  virtual void loadSystemMemoryUsage() = 0;
 
   /// Returns current bytes allocated by malloc. The returned value is used to
   /// compare with 'Config::mallocBytesUsageDumpThreshold'

presto-native-execution/presto_cpp/main/PrestoServer.cpp

@@ -1530,7 +1530,7 @@ void PrestoServer::checkOverload() {
       systemConfig->workerOverloadedThresholdMemGb() * 1024 * 1024 * 1024;
   if (overloadedThresholdMemBytes > 0) {
     const auto currentUsedMemoryBytes = (memoryChecker_ != nullptr)
-        ? memoryChecker_->cachedSystemUsedMemoryBytes()
+        ? memoryChecker_->systemUsedMemoryBytes()
         : 0;
     const bool memOverloaded =
         (currentUsedMemoryBytes > overloadedThresholdMemBytes);

presto-native-execution/presto_cpp/main/tests/PeriodicMemoryCheckerTest.cpp

@@ -34,10 +34,11 @@ class PeriodicMemoryCheckerTest : public testing::Test {
         std::function<void()>&& periodicCb = nullptr,
         std::function<bool(const std::string&)>&& heapDumpCb = nullptr)
         : PeriodicMemoryChecker(config),
-          systemUsedMemoryBytes_(systemUsedMemoryBytes),
           mallocBytes_(mallocBytes),
           periodicCb_(std::move(periodicCb)),
-          heapDumpCb_(std::move(heapDumpCb)) {}
+          heapDumpCb_(std::move(heapDumpCb)) {
+            cachedSystemUsedMemoryBytes_ = systemUsedMemoryBytes;
+          }
 
     ~TestPeriodicMemoryChecker() override {}
 
@@ -46,9 +47,7 @@ class PeriodicMemoryCheckerTest : public testing::Test {
     }
 
    protected:
-    int64_t systemUsedMemoryBytes() override {
-      return systemUsedMemoryBytes_;
-    }
+    void loadSystemMemoryUsage() override {}
 
     int64_t mallocBytes() const override {
       return mallocBytes_;
@@ -70,7 +69,6 @@ class PeriodicMemoryCheckerTest : public testing::Test {
     void removeDumpFile(const std::string& filePath) const override {}
 
    private:
-    int64_t systemUsedMemoryBytes_{0};
     int64_t mallocBytes_{0};
     std::function<void()> periodicCb_;
     std::function<bool(const std::string&)> heapDumpCb_;