Attempts to remove an element from one of the InnerPQs up to maxRetries
times.
The source is chosen randomly among the InnerPQs that are not being
operated on by other threads.
With low contention, the expected rank of the removed element is width. With
high contention, the expected average rank of concurrently-removed elements
is width. The expected maximum rank is O(width log(width)).
A removed element, or null if each attempt failed.
Progress: Lock-free if there are no more than width total concurrent threads,
otherwise deadlock-free.
Attempts to remove an element from one of the InnerPQs up to maxRetries times.
The source is chosen randomly among the InnerPQs that are not being operated on by other threads. With low contention, the expected rank of the removed element is width. With high contention, the expected average rank of concurrently-removed elements is width. The expected maximum rank is O(width log(width)).