only a part of VolatileGlobalCellCache.createGlobal() needs to be synchronized

src/main/java/bdv/img/cache/VolatileGlobalCellCache.java

@@ -407,11 +407,13 @@ public class VolatileGlobalCellCache< A extends VolatileAccess > implements Cach
 	 *
 	 * @return a cell with the specified coordinates.
 	 */
-	public synchronized VolatileCell< A > createGlobal( final int[] cellDims, final long[] cellMin, final int timepoint, final int setup, final int level, final int index, final LoadingStrategy loadingStrategy )
+	public VolatileCell< A > createGlobal( final int[] cellDims, final long[] cellMin, final int timepoint, final int setup, final int level, final int index, final LoadingStrategy loadingStrategy )
 	{
 		final Key k = new Key( timepoint, setup, level, index );
 		Entry entry = null;
 
+		synchronized ( softReferenceCache )
+		{
 			final Reference< Entry > ref = softReferenceCache.get( k );
 			if ( ref != null )
 				entry = ref.get();
@@ -422,6 +424,7 @@ public class VolatileGlobalCellCache< A extends VolatileAccess > implements Cach
 				entry = new Entry( k, cell );
 				softReferenceCache.put( k, new WeakReference< Entry >( entry ) );
 			}
+		}
 
 		switch ( loadingStrategy )
 		{