AXIS2-6099 Add http/2 features in new JSON packages moshih2 and gsonh2, with default parameters set up for a reasonably tuned config by default

Author: robertlazarski

modules/json/src/org/apache/axis2/json/gsonh2/EnhancedGsonJsonBuilder.java

@@ -65,7 +65,7 @@
  * - Intelligent output streaming based on response size and complexity
  * - Memory management with buffer optimization for large responses
  * - Performance metrics collection for response generation analysis
- * - Field-specific output optimizations for RAPI-style data patterns
+ * - Field-specific output optimizations for JSON-style data patterns
  * - Flow control patterns during response generation (from HTTP2FlowController concepts)
  * - Streaming configuration based on payload characteristics
  *
@@ -77,7 +77,7 @@
  * - 30-50% performance improvement for large JSON responses (>1MB)
  * - Reduced memory usage through intelligent buffering and streaming
  * - Better throughput for concurrent JSON response generation
- * - Specialized optimization for RAPI-style response patterns
+ * - Specialized optimization for JSON-style response patterns
  * - Prevents blocking behavior during large response generation
  */
 public class EnhancedMoshiJsonFormatter implements MessageFormatter {
@@ -148,7 +148,7 @@ public void writeTo(MessageContext outMsgCtxt, OMOutputFormat omOutputFormat, Ou
                 if (log.isDebugEnabled()) {
                     log.debug("EnhancedMoshiH2Formatter: [" + responseId + "] Large response detected - suggesting GC optimization");
                 }
-                suggestGarbageCollectionForResponse();
+                monitorMemoryPressureForResponse();
             }
 
             // Generate response with appropriate strategy
@@ -245,7 +245,7 @@ private void generateLargeResponseOptimized(MessageContext outMsgCtxt, OMOutputF
         // Apply memory optimization patterns (from HTTP/2 integration)
         if (strategy.getEstimatedSize() > MEMORY_OPTIMIZATION_THRESHOLD) {
             log.debug("Applying memory optimization for very large response: " + responseId);
-            suggestGarbageCollectionForResponse();
+            monitorMemoryPressureForResponse();
         }
 
         generateWithEnhancedMoshi(outMsgCtxt, omOutputFormat, outputStream, preserve, strategy, responseId);
@@ -429,7 +429,7 @@ private void generateCollectionResponseOptimized(java.util.Collection<?> collect
 
                 if (itemCount % 5000 == 0) {
                     // Memory management for very large collections
-                    suggestGarbageCollectionForResponse();
+                    monitorMemoryPressureForResponse();
 
                     if (log.isDebugEnabled()) {
                         log.debug("Processed " + itemCount + " collection items for response: " + responseId);
@@ -520,13 +520,26 @@ private String generateResponseId() {
     }
 
     /**
-     * Memory management for large responses (pattern from HTTP/2 integration).
+     * Memory pressure monitoring for large responses.
+     * Note: Removed System.gc() call - libraries should not interfere with application GC strategy.
      */
-    private void suggestGarbageCollectionForResponse() {
+    private void monitorMemoryPressureForResponse() {
         if (log.isDebugEnabled()) {
-            log.debug("Suggesting garbage collection for Enhanced Moshi H2 large response generation");
+            Runtime runtime = Runtime.getRuntime();
+            long totalMemory = runtime.totalMemory();
+            long freeMemory = runtime.freeMemory();
+            long usedMemory = totalMemory - freeMemory;
+            double memoryUsage = (double) usedMemory / totalMemory * 100;
+
+            log.debug("Memory pressure monitoring during large response generation: "
+                + String.format("%.1f%% used (%s / %s)", memoryUsage,
+                formatBytes(usedMemory), formatBytes(totalMemory)));
+
+            if (memoryUsage > 85.0) {
+                log.warn("High memory pressure detected (" + String.format("%.1f", memoryUsage) + "% used) during JSON response generation. " +
+                        "Consider increasing heap size or reducing response size.");
+            }
         }
-        System.gc();
     }
 
     /**
@@ -682,7 +695,7 @@ public void writeStartElement(String localName) throws XMLStreamException {
 
             // Apply memory optimization for large responses
             if (strategy.isLargeResponse() && shouldOptimizeMemory()) {
-                optimizeMemoryForLargeResponse();
+                monitorMemoryForLargeResponse();
             }
 
             // Call parent implementation
@@ -714,7 +727,7 @@ public void writeCharacters(String text) throws XMLStreamException {
 
             // Memory pressure monitoring for very large text content
             if (text.length() > 10000 && shouldOptimizeMemory()) {
-                optimizeMemoryForLargeResponse();
+                monitorMemoryForLargeResponse();
             }
         }
 
@@ -794,20 +807,33 @@ private boolean shouldOptimizeMemory() {
         }
 
         /**
-         * Apply memory optimization for large responses.
+         * Monitor memory pressure during large response processing.
+         * Note: Removed System.gc() call - libraries should not interfere with application GC strategy.
          */
-        private void optimizeMemoryForLargeResponse() {
+        private void monitorMemoryForLargeResponse() {
             long currentTime = System.nanoTime();
 
-            // Avoid too frequent GC hints (max once per 5 seconds)
+            // Avoid too frequent memory checks (max once per 5 seconds)
             if (currentTime - lastGcHint > 5_000_000_000L) {
+                Runtime runtime = Runtime.getRuntime();
+                long totalMemory = runtime.totalMemory();
+                long freeMemory = runtime.freeMemory();
+                long usedMemory = totalMemory - freeMemory;
+                double memoryUsage = (double) usedMemory / totalMemory * 100;
+
                 if (enhancedLog.isDebugEnabled()) {
-                    enhancedLog.debug("EnhancedMoshiXMLStreamWriter: [" + responseId + "] Suggesting GC for memory optimization");
+                    enhancedLog.debug("EnhancedMoshiXMLStreamWriter: [" + responseId + "] Memory monitoring: "
+                        + String.format("%.1f%% used (%s / %s)", memoryUsage,
+                        formatBytesLocal(usedMemory), formatBytesLocal(totalMemory)));
+                }
+
+                if (memoryUsage > 85.0) {
+                    enhancedLog.warn("High memory pressure detected (" + String.format("%.1f", memoryUsage) + "% used) in XML stream writer. " +
+                            "Consider increasing heap size.");
                 }
 
-                System.gc(); // Hint for garbage collection
                 lastGcHint = currentTime;
-                memoryOptimized = true;
+                memoryOptimized = true; // Keep this flag to indicate memory monitoring occurred
             }
         }