Major Description
Assume following case (operations are going concurrently):
1) Client1 -> offer. Add new index in queue.
2) On Client1 happens JVM pause or short-time problem with connectivity to cluster longer than 3 sec.
3) Client2 -> poll. Get index from cache, but no value available.
4) Client2 checks for value about 3 sec and if no value appears, just skips it.
Should be fixed somehow or make timeout configurable.