public BlockingCompactionContext waitForBlocking() {
      while (this.blocked == null || !this.blocked.isInCompact) {
        Threads.sleepWithoutInterrupt(50);
      }
      BlockingCompactionContext ctx = this.blocked;
      this.blocked = null;
      return ctx;
    }
HBASE-7947: Regression test to ensure adding to the correct list in the {@link CompactSplit}
@throws Exception on failure
hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestCompaction.java