GH-622 cache StackTraceElement instances

Author: thurka

visualvm/jfr/src/org/graalvm/visualvm/jfr/views/sampler/CPUSamplerViewSupport.java

@@ -78,6 +78,7 @@ static final class CPUViewSupport extends JPanel implements JFREventVisitor {
 
         private List<JFREventWithStack> data;
         private Set<String> ignoredEvents;
+        private JFRThreadInfoSupport tiSupport;
 
 
         CPUViewSupport(JFRModel model) {
@@ -95,6 +96,7 @@ public void init() {
             if (hasData) {
                 data = new ArrayList<>();
                 ignoredEvents = new HashSet<>();
+                tiSupport = new JFRThreadInfoSupport();
             }
         }
 
@@ -104,7 +106,7 @@ public boolean visit(String typeName, JFREvent event) {
 
             try {
                 if (!ignoredEvents.contains(typeName))
-                    data.add(new JFREventWithStack(typeName, event, model));
+                    data.add(new JFREventWithStack(typeName, event, model, tiSupport));
             } catch (JFRPropertyNotAvailableException e) {
                 ignoredEvents.add(typeName);
             }
@@ -132,6 +134,7 @@ public void done() {
 
                 data = null;
                 ignoredEvents = null;
+                tiSupport = null;
                 threads = null;
 
                 try {
@@ -200,7 +203,7 @@ private static class JFREventWithStack implements Comparable<JFREventWithStack>
         private final Map<String, Object> threadInfo;
 
 
-        JFREventWithStack(String type, JFREvent event, JFRModel model) throws JFRPropertyNotAvailableException {
+        JFREventWithStack(String type, JFREvent event, JFRModel model, JFRThreadInfoSupport tiSupport) throws JFRPropertyNotAvailableException {
             JFRStackTrace stack;
             if ("jdk.ThreadEnd".equals(type)) { // NOI18N
                 stack = null;
@@ -219,8 +222,8 @@ private static class JFREventWithStack implements Comparable<JFREventWithStack>
             if (eventTimeI == null) throw new JFRPropertyNotAvailableException("Must define eventTime to include into sampled snapshot"); // NOI18N
             eventTime = ValuesConverter.instantToRelativeNanos(eventTimeI, model);
 
-            if (profilingEvent) threadInfo = JFRThreadInfoSupport.getThreadInfo(thread, stack, event.getString("state")); // NOI18N
-            else threadInfo = JFRThreadInfoSupport.getThreadInfo(thread, stack, getState(type));
+            if (profilingEvent) threadInfo = tiSupport.getThreadInfo(thread, stack, event.getString("state")); // NOI18N
+            else threadInfo = tiSupport.getThreadInfo(thread, stack, getState(type));
         }
 
 

visualvm/jfr/src/org/graalvm/visualvm/jfr/views/sampler/JFRThreadInfoSupport.java

@@ -41,11 +41,17 @@ final class JFRThreadInfoSupport {
     static final String THREAD_ID = "tid"; // NOI18N
     static final String THREAD_STACK = "stack"; // NOI18N
 
-    static Map<String,Object> getThreadInfo(JFRThread thread, JFRStackTrace stack, String state) {
+    private final Map<StackTraceElement,StackTraceElement> cache;
+
+    JFRThreadInfoSupport() {
+        cache = new HashMap<>();
+    }
+
+    Map<String,Object> getThreadInfo(JFRThread thread, JFRStackTrace stack, String state) {
         return getThreadInfo(thread, stack, state(state));
     }
 
-    static Map<String,Object> getThreadInfo(JFRThread thread, JFRStackTrace stack, Thread.State state) {
+    Map<String,Object> getThreadInfo(JFRThread thread, JFRStackTrace stack, Thread.State state) {
         Map<String,Object> threadInfo = new HashMap<>();
 
         Long id = Long.valueOf(thread.getId());
@@ -61,7 +67,7 @@ static Map<String,Object> getThreadInfo(JFRThread thread, JFRStackTrace stack, T
     }
 
 
-    private static StackTraceElement[] stackTrace(JFRStackTrace stack) {
+    private StackTraceElement[] stackTrace(JFRStackTrace stack) {
         List<JFRStackFrame> frames = stack.getFrames();
         StackTraceElement[] elements = new StackTraceElement[frames.size()];
 
@@ -71,7 +77,7 @@ private static StackTraceElement[] stackTrace(JFRStackTrace stack) {
         return elements;
     }
 
-    private static StackTraceElement stackTraceElement(JFRStackFrame frame) {
+    private StackTraceElement stackTraceElement(JFRStackFrame frame) {
         JFRMethod method = frame.getMethod();
 
         String className = method == null ? null : method.getType().getName(); // NOI18N
@@ -82,7 +88,8 @@ private static StackTraceElement stackTraceElement(JFRStackFrame frame) {
 
         int lineNumber = "Native".equals(frame.getType()) ? -2 : frame.getLine(); // NOI18N
 
-        return new StackTraceElement(className, methodName, null, lineNumber);
+        StackTraceElement el = new StackTraceElement(className, methodName, null, lineNumber);
+        return cache.computeIfAbsent(el, v -> el);
     }
 
     private static Thread.State state(String state) {