QPID-541 A large portion of memory was being wasted in 32k ByteBuffers being held by the AMQShortStrings.

Patch submitted by Robert Godfrey to intern() the AMQSSs to reduce memory usage. Current implementation *will* impact performance due to the usage of a static Map for storage. However, a thread local implementation is in the works.


git-svn-id: https://svn.apache.org/repos/asf/incubator/qpid/branches/M2@556890 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 31 insertions, 1 deletions

diff --git a/java/common/src/main/java/org/apache/qpid/framing/AMQShortString.java b/java/common/src/main/java/org/apache/qpid/framing/AMQShortString.java
index 05e9473463..ec29d62847 100644
--- a/java/common/src/main/java/org/apache/qpid/framing/AMQShortString.java
+++ b/java/common/src/main/java/org/apache/qpid/framing/AMQShortString.java
@@ -26,6 +26,10 @@ import org.apache.mina.common.ByteBuffer;
 import org.slf4j.Logger;

 import org.slf4j.LoggerFactory;

 

+import java.util.Map;

+import java.util.WeakHashMap;

+import java.lang.ref.WeakReference;

+

 /**

  * A short string is a representation of an AMQ Short String

  * Short strings differ from the Java String class by being limited to on ASCII characters (0-127)

@@ -34,6 +38,10 @@ import org.slf4j.LoggerFactory;
  */

 public final class AMQShortString implements CharSequence, Comparable<AMQShortString>

 {

+

+    private static final Map<AMQShortString, WeakReference<AMQShortString>> internMap =

+            new WeakHashMap<AMQShortString, WeakReference<AMQShortString>>();

+

     private static final Logger _logger = LoggerFactory.getLogger(AMQShortString.class);

 

     private final ByteBuffer _data;

@@ -43,7 +51,6 @@ public final class AMQShortString implements CharSequence, Comparable<AMQShortSt
 

     public AMQShortString(byte[] data)

     {

-

         _data = ByteBuffer.wrap(data);

         _length = data.length;

     }

@@ -376,4 +383,27 @@ public final class AMQShortString implements CharSequence, Comparable<AMQShortSt
             return (length() == name.length()) ? 0 : -1;

         }

     }

+

+

+    public AMQShortString intern()

+    {

+        hashCode();

+        synchronized(internMap)

+        {

+

+            WeakReference<AMQShortString> ref = internMap.get(this);

+            if(ref != null)

+            {

+                AMQShortString internString = ref.get();

+                if(internString != null)

+                {

+                    return internString;

+                }

+            }

+

+            AMQShortString internString = new AMQShortString(getBytes());

+            internMap.put(internString, new WeakReference(internString));

+            return internString;

+        }

+    }

 }