V8 memory usage statistics

libraries/script-engine/src/ScriptEngine.h

@@ -46,6 +46,14 @@ inline ScriptValue scriptValueFromValue(ScriptEngine* engine, const T& t);
 template <typename T>
 inline T scriptvalue_cast(const ScriptValue& value);
 
+class ScriptEngineMemoryStatistics {
+public:
+    size_t totalHeapSize;
+    size_t usedHeapSize;
+    size_t totalAvailableSize;
+    size_t totalGlobalHandlesSize;
+    size_t usedGlobalHandlesSize;
+};
 
 /**
  * @brief Provides an engine-independent interface for a scripting engine
@@ -374,6 +382,16 @@ public:
      * @param title Informative title for the backtrace
      */
     virtual void logBacktrace(const QString &title) = 0;
+
+    /**
+     * @brief Return memory usage statistics data.
+     *
+     * Returns memory usage statistics data for debugging.
+     *
+     * @return ScriptEngineMemoryStatistics Object containing memory usage statistics data.
+     */
+    virtual ScriptEngineMemoryStatistics getMemoryUsageStatistics() = 0;
+
 public:
     // helper to detect and log warnings when other code invokes QScriptEngine/BaseScriptEngine in thread-unsafe ways
     bool IS_THREADSAFE_INVOCATION(const QString& method);

libraries/script-engine/src/ScriptManagerScriptingInterface.cpp

@@ -12,6 +12,7 @@
 
 #include "ScriptManager.h"
 #include "ScriptManagerScriptingInterface.h"
+#include "ScriptEngine.h"
 #include <QMetaType>
 
 
@@ -43,11 +44,22 @@
     connect(_manager, &ScriptManager::entityScriptDetailsUpdated, this, &ScriptManagerScriptingInterface::entityScriptDetailsUpdated);
     connect(_manager, &ScriptManager::entityScriptPreloadFinished, this, &ScriptManagerScriptingInterface::entityScriptPreloadFinished);
     connect(_manager, &ScriptManager::unhandledException, this, &ScriptManagerScriptingInterface::scriptManagerException);
-    }
+}
 
-    void ScriptManagerScriptingInterface::scriptManagerException(std::shared_ptr<ScriptException> exception) {
+void ScriptManagerScriptingInterface::scriptManagerException(std::shared_ptr<ScriptException> exception) {
     // V8TODO: What should we actually handle here?
 
 
     // emit unhandledException(exception.thrownValue);
-    }
+}
+
+QVariantMap ScriptManagerScriptingInterface::getMemoryUsageStatistics() {
+    auto statistics = _manager->engine()->getMemoryUsageStatistics();
+    QVariantMap map;
+    map.insert("totalHeapSize", QVariant((qulonglong)(statistics.totalHeapSize)));
+    map.insert("usedHeapSize", QVariant((qulonglong)(statistics.usedHeapSize)));
+    map.insert("totalAvailableSize", QVariant((qulonglong)(statistics.totalAvailableSize)));
+    map.insert("totalGlobalHandlesSize", QVariant((qulonglong)(statistics.totalGlobalHandlesSize)));
+    map.insert("usedGlobalHandlesSize", QVariant((qulonglong)(statistics.usedGlobalHandlesSize)));
+    return map;
+}

libraries/script-engine/src/ScriptManagerScriptingInterface.h

@@ -479,6 +479,30 @@ public:
      */
     Q_INVOKABLE QString getExternalPath(ExternalResource::Bucket bucket, const QString& path) { return _manager->getExternalPath(bucket, path); }
 
+    /**jsdoc
+     * <p>Object containing memory usage statistics data.</p>
+     * <table>
+     *   <thead>
+     *     <tr><th>Name</th><th>Type</th><th>Description</th></tr>
+     *   </thead>
+     *   <tbody>
+     *     <tr><td><code>totalHeapSize</code></td><td>{number}</td><td>Total heap size allocated by scripting engine.</td></tr>
+     *     <tr><td><code>usedHeapSize</code></td><td>{number}</td><td></td>Amount of heap memory that is currently in use.</tr>
+     *     <tr><td><code>totalAvailableSize</code></td><td>{number}</td><td>Amount of remaining available heap memory</td></tr>
+     *     <tr><td><code>totalGlobalHandlesSize</code></td><td>{number}</td><td>V8-specific property</td></tr>
+     *     <tr><td><code>usedGlobalHandlesSize</code></td><td>{number}</td><td>V8-specific property</td></tr>
+     *   </tbody>
+     * </table>
+     * @typedef {object} Script.MemoryUsageData
+     */
+
+    /**jsdoc
+     * Returns memory usage statistics data.
+     * @function Script.getMemoryUsageStatistics
+     * @Returns {Script.MemoryUsageData} Object containing statistics about memory usage.
+     */
+    Q_INVOKABLE QVariantMap getMemoryUsageStatistics();
+
 signals:
 
     /**jsdoc

libraries/script-engine/src/v8/ScriptEngineV8.cpp

@@ -1708,3 +1708,18 @@ QStringList ScriptEngineV8::getCurrentScriptURLs() const {
     }
     return scriptURLs;
 }
+
+ScriptEngineMemoryStatistics ScriptEngineV8::getMemoryUsageStatistics() {
+    v8::Locker locker(_v8Isolate);
+    v8::Isolate::Scope isolateScope(_v8Isolate);
+    ScriptEngineMemoryStatistics statistics;
+    v8::HeapStatistics heapStatistics;
+    _v8Isolate->GetHeapStatistics(&heapStatistics);
+    statistics.totalHeapSize = heapStatistics.total_available_size();
+    statistics.usedHeapSize = heapStatistics.used_heap_size();
+    statistics.totalAvailableSize = heapStatistics.total_available_size();
+    statistics.totalGlobalHandlesSize = heapStatistics.total_global_handles_size();
+    statistics.usedGlobalHandlesSize = heapStatistics.used_global_handles_size();
+
+    return statistics;
+}

libraries/script-engine/src/v8/ScriptEngineV8.h

@@ -135,6 +135,7 @@ public:  // ScriptEngine implementation
     virtual QString scriptValueDebugListMembers(const ScriptValue &value) override;
     QString scriptValueDebugListMembersV8(const V8ScriptValue &v8Value);
     virtual void logBacktrace(const QString &title = QString("")) override;
+    virtual ScriptEngineMemoryStatistics getMemoryUsageStatistics() override;
 
     // helper to detect and log warnings when other code invokes QScriptEngine/BaseScriptEngine in thread-unsafe ways
     inline bool IS_THREADSAFE_INVOCATION(const QString& method) { return ScriptEngine::IS_THREADSAFE_INVOCATION(method); }

scripts/developer/debugging/scriptMemoryReport.js

@@ -0,0 +1,27 @@
+//
+//  scriptMemoryReport.js
+//  scripts/developer/debugging
+//
+//  Created by dr Karol Suprynowicz on 2023/04/23
+//  Copyright 2023 Overte e.V.
+//
+//  Distributed under the Apache License, Version 2.0.
+//  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
+//  SPDX-License-Identifier: Apache-2.0
+//
+
+// A simple script that prints memory usage statistics for a given script engine every 5 seconds
+// It can be included for example as a part of default scripts or controller scripts
+
+var memoryStatisticsIntervalHandle = Script.setInterval(function () {
+    statistics = Script.getMemoryUsageStatistics();
+    print("Script memory usage: Total heap size: " + statistics.totalHeapSize
+        + " usedHeapSize: " + statistics.usedHeapSize
+        + " totalAvailableSize: " + statistics.totalAvailableSize
+        + " totalGlobalHandlesSize: " + statistics.totalGlobalHandlesSize
+        + " usedGlobalHandlesSize: " + statistics.usedGlobalHandlesSize);
+}, 5000);
+
+Script.scriptEnding.connect(function () {
+    Script.clearInterval(memoryStatisticsIntervalHandle);
+});