fairness of swapper burst eviction

In plasma, burst eviction can be performed by writer, reader and worker. If it is performed by writer and reader, it evicts pages from which the index in which the writer/reader is acting upon (using local clock). If it is performed by worker, it use the global clock to sweep through multiple indexes. If there are more writer/reader goroutines than worker goroutines, the heavily used index may get evicted more often than the lightly used indexes.