GZIPInputStream is not closed at all at places, where it's instantiated, which leads to off-heap memory leak with every deserialized message.

GZIPInputStream uses Inflater internally (so also native zlib). Inflater frees up memory only on explicit call to end() or during finalization (finalize() contains only call to end()), so GZIPInputStream should always be explicitly closed.

As native libraries are used a non-scalaish try-finally is used to avoid off-heap memory leak for GZIPInputStream and GZIPOutputStream in case of exceptions.

akka-distributed-data/src/main/scala/akka/cluster/ddata/protobuf/SerializationSupport.scala

@@ -56,8 +56,8 @@ trait SerializationSupport {
   def compress(msg: MessageLite): Array[Byte] = {
     val bos = new ByteArrayOutputStream(BufferSize)
     val zip = new GZIPOutputStream(bos)
-    msg.writeTo(zip)
-    zip.close()
+    try msg.writeTo(zip)
+    finally zip.close()
     bos.toByteArray
   }
 
@@ -73,7 +73,8 @@ trait SerializationSupport {
         readChunk()
     }
 
-    readChunk()
+    try readChunk()
+    finally in.close()
     out.toByteArray
   }