// sort the payloads by page id as a deadlock avoidance measure, out
// of order updates may result in deadlock with the addHitsAndSetAccessTime method
List<PageStatsPayload> sorted = sortPayloads(statsUpdates);
for (PageStatsPayload payload : sorted) {
// verify the stats are referring to an existing tile set id
TileSet tset = payload.getTileSet();
if (tset == null) {
String tileSetId = payload.getPage().getTileSetId();
tset = getTileSetByIdInternal(tileSetId);
if (tset == null) {
log.warn("Could not locate tileset with id " + tileSetId