[SYSTEMML-1325] Fixed GPU cleanup bug when invoked with JMLC.

Closes apache#854.

Author: Niketan Pansare

src/main/java/org/apache/sysml/runtime/controlprogram/caching/CacheableData.java

@@ -624,15 +624,19 @@ public synchronized void clearData()
 			_rddHandle.setBackReference(null);
 		if( _bcHandle != null )
 			_bcHandle.setBackReference(null);
+		clearGPUData();
+		
+		// change object state EMPTY
+		setDirty(false);
+		setEmpty();
+	}
+	
+	public void clearGPUData() {
 		if( _gpuObjects != null ) {
 			for (GPUObject gObj : _gpuObjects.values())
 				if (gObj != null)
 					gObj.clearData(null, gObj.getGPUContext().EAGER_CUDA_FREE);
 		}
-		
-		// change object state EMPTY
-		setDirty(false);
-		setEmpty();
 	}
 
 	public synchronized void exportData() {

src/main/java/org/apache/sysml/runtime/controlprogram/context/ExecutionContext.java

@@ -648,8 +648,12 @@ public void cleanupCacheableData(CacheableData<?> mo) {
 			Statistics.removeCPMemObject(System.identityHashCode(mo));
 		//early abort w/o scan of symbol table if no cleanup required
 		boolean fileExists = (mo.isHDFSFileExists() && mo.getFileName() != null);
-		if( !CacheableData.isCachingActive() && !fileExists )
+		if( !CacheableData.isCachingActive() && !fileExists ) {
+			if ( mo.isCleanupEnabled() && !getVariables().hasReferences(mo) )
+				mo.clearGPUData();
 			return;
+		}
+			
 
 		try {
 			//compute ref count only if matrix cleanup actually necessary