8298276: JFR: Update NMT events to make use of common periodic timestamp feature

Reviewed-by: mgronlun

Author: egahlin

…otspot/share/services/memJfrReporter.cpp …re/jfr/periodic/jfrNativeMemoryEvent.cppsrc/hotspot/share/services/memJfrReporter.cpp renamed to src/hotspot/share/jfr/periodic/jfrNativeMemoryEvent.cpp src/hotspot/share/services/memJfrReporter.cpp renamed to src/hotspot/share/jfr/periodic/jfrNativeMemoryEvent.cpp

@@ -24,59 +24,37 @@
 
 #include "precompiled.hpp"
 #include "jfr/jfrEvents.hpp"
-#include "services/memJfrReporter.hpp"
+#include "jfr/periodic/jfrNativeMemoryEvent.hpp"
 #include "services/memTracker.hpp"
 #include "services/nmtUsage.hpp"
 #include "utilities/globalDefinitions.hpp"
 #include "utilities/ticks.hpp"
 
-// Helper class to avoid refreshing the NMTUsage to often and allow
-// the two JFR events to use the same data.
-class MemJFRCurrentUsage : public AllStatic {
-private:
-  // The age threshold in milliseconds. If older than this refresh the usage.
-  static const uint64_t AgeThreshold = 50;
+static NMTUsage* get_usage(const Ticks& timestamp) {
+  static Ticks last_timestamp;
+  static NMTUsage* usage = nullptr;
 
-  static Ticks _timestamp;
-  static NMTUsage* _usage;
-
-public:
-  static NMTUsage* get_usage();
-  static Ticks get_timestamp();
-};
-
-Ticks MemJFRCurrentUsage::_timestamp;
-NMTUsage* MemJFRCurrentUsage::_usage = nullptr;
-
-NMTUsage* MemJFRCurrentUsage::get_usage() {
-  Tickspan since_baselined = Ticks::now() - _timestamp;
-
-  if (_usage == nullptr) {
+  if (usage == nullptr) {
     // First time, create a new NMTUsage.
-    _usage = new NMTUsage(NMTUsage::OptionsNoTS);
-  } else if (since_baselined.milliseconds() < AgeThreshold) {
-    // There is recent enough usage information, return it.
-    return _usage;
+    usage = new NMTUsage(NMTUsage::OptionsNoTS);
+    usage->refresh();
+    last_timestamp = timestamp;
   }
 
-  // Refresh the usage information.
-  _usage->refresh();
-  _timestamp.stamp();
-
-  return _usage;
-}
-
-Ticks MemJFRCurrentUsage::get_timestamp() {
-  return _timestamp;
+  if (timestamp != last_timestamp) {
+    // Refresh usage if new timestamp.
+    usage->refresh();
+    last_timestamp = timestamp;
+  }
+  return usage;
 }
 
-void MemJFRReporter::send_total_event() {
+void JfrNativeMemoryEvent::send_total_event(const Ticks& timestamp) {
   if (!MemTracker::enabled()) {
     return;
   }
 
-  NMTUsage* usage = MemJFRCurrentUsage::get_usage();
-  Ticks timestamp = MemJFRCurrentUsage::get_timestamp();
+  NMTUsage* usage = get_usage(timestamp);
 
   EventNativeMemoryUsageTotal event(UNTIMED);
   event.set_starttime(timestamp);
@@ -85,7 +63,7 @@ void MemJFRReporter::send_total_event() {
   event.commit();
 }
 
-void MemJFRReporter::send_type_event(const Ticks& starttime, MEMFLAGS flag, size_t reserved, size_t committed) {
+void JfrNativeMemoryEvent::send_type_event(const Ticks& starttime, MEMFLAGS flag, size_t reserved, size_t committed) {
   EventNativeMemoryUsage event(UNTIMED);
   event.set_starttime(starttime);
   event.set_type(NMTUtil::flag_to_index(flag));
@@ -94,13 +72,12 @@ void MemJFRReporter::send_type_event(const Ticks& starttime, MEMFLAGS flag, size
   event.commit();
 }
 
-void MemJFRReporter::send_type_events() {
+void JfrNativeMemoryEvent::send_type_events(const Ticks& timestamp) {
   if (!MemTracker::enabled()) {
     return;
   }
 
-  NMTUsage* usage = MemJFRCurrentUsage::get_usage();
-  Ticks timestamp = MemJFRCurrentUsage::get_timestamp();
+  NMTUsage* usage = get_usage(timestamp);
 
   for (int index = 0; index < mt_number_of_types; index ++) {
     MEMFLAGS flag = NMTUtil::index_to_flag(index);

…otspot/share/services/memJfrReporter.hpp …re/jfr/periodic/jfrNativeMemoryEvent.hppsrc/hotspot/share/services/memJfrReporter.hpp renamed to src/hotspot/share/jfr/periodic/jfrNativeMemoryEvent.hpp src/hotspot/share/services/memJfrReporter.hpp renamed to src/hotspot/share/jfr/periodic/jfrNativeMemoryEvent.hpp

@@ -22,8 +22,8 @@
  *
  */
 
-#ifndef SHARE_SERVICES_MEMJFRREPORTER_HPP
-#define SHARE_SERVICES_MEMJFRREPORTER_HPP
+#ifndef SHARE_JFR_PERIODIC_JFRNATIVEMEMORYEVENT_HPP
+#define SHARE_JFR_PERIODIC_JFRNATIVEMEMORYEVENT_HPP
 
 #include "memory/allocation.hpp"
 #include "services/nmtUsage.hpp"
@@ -33,12 +33,12 @@
 // MemJFRReporter is only used by threads sending periodic JFR
 // events. These threads are synchronized at a higher level,
 // so no more synchronization is needed.
-class MemJFRReporter : public AllStatic {
+class JfrNativeMemoryEvent : public AllStatic {
 private:
   static void send_type_event(const Ticks& starttime, MEMFLAGS flag, size_t reserved, size_t committed);
  public:
-  static void send_total_event();
-  static void send_type_events();
+  static void send_total_event(const Ticks& timestamp);
+  static void send_type_events(const Ticks& timestamp);
 };
 
-#endif //SHARE_SERVICES_MEMJFRREPORTER_HPP
+#endif //SHARE_JFR_PERIODIC_JFRNATIVEMEMORYEVENT_HPP

src/hotspot/share/jfr/periodic/jfrPeriodic.cpp

@@ -41,6 +41,7 @@
 #include "jfr/periodic/jfrOSInterface.hpp"
 #include "jfr/periodic/jfrThreadCPULoadEvent.hpp"
 #include "jfr/periodic/jfrThreadDumpEvent.hpp"
+#include "jfr/periodic/jfrNativeMemoryEvent.hpp"
 #include "jfr/periodic/jfrNetworkUtilization.hpp"
 #include "jfr/recorder/jfrRecorder.hpp"
 #include "jfr/utilities/jfrThreadIterator.hpp"
@@ -63,7 +64,6 @@
 #include "runtime/vm_version.hpp"
 #include "services/classLoadingService.hpp"
 #include "services/management.hpp"
-#include "services/memJfrReporter.hpp"
 #include "services/threadService.hpp"
 #include "utilities/exceptions.hpp"
 #include "utilities/globalDefinitions.hpp"
@@ -643,9 +643,9 @@ TRACE_REQUEST_FUNC(FinalizerStatistics) {
 }
 
 TRACE_REQUEST_FUNC(NativeMemoryUsage) {
-  MemJFRReporter::send_type_events();
+  JfrNativeMemoryEvent::send_type_events(timestamp());
 }
 
 TRACE_REQUEST_FUNC(NativeMemoryUsageTotal) {
-  MemJFRReporter::send_total_event();
+  JfrNativeMemoryEvent::send_total_event(timestamp());
 }

test/jdk/jdk/jfr/event/runtime/TestNativeMemoryUsageEvents.java

@@ -25,7 +25,9 @@
 
 import static jdk.test.lib.Asserts.assertGreaterThan;
 import static jdk.test.lib.Asserts.assertTrue;
+import static jdk.test.lib.Asserts.assertEquals;
 
+import java.time.Instant;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -132,6 +134,12 @@ private static void verifyExpectedEventTypes(List<RecordedEvent> events) throws
         for (String type : UsageEventTypes) {
             assertTrue(uniqueEventTypes.contains(type), "Events should include: " + type);
         }
+        // Verify that events only have two timestamps
+        List<Instant> timestamps = events.stream()
+                .map(e -> e.getStartTime())
+                .distinct()
+                .toList();
+        assertEquals(timestamps.size(), 2, "Expected two timestamps: " + timestamps);
     }
 
     private static void verifyHeapGrowth(List<RecordedEvent> events) throws Exception {