ConcurrentMap<String, Task> getTasks() {
    return tasks;
  }
Get the amount of time in milliseconds to wait till next check. Check less frequently if a
bunch of work to do still. At a max, check every minute. At a minimum, check every 100ms. This
is to alleviate case where perhaps there are a bunch of threads waiting on a completion. For
example, if the zk-based implementation, we will scan the '/hbase/splitWAL' dir every time
through this loop. If there are lots of WALs to split -- could be tens of thousands if big
cluster -- then it will take a while. If the Master has many SCPs waiting on wal splitting --
could be up to 10 x the configured PE thread count (default would be 160) -- then the Master
will be putting up a bunch of load on zk.
hbase-server/src/main/java/org/apache/hadoop/hbase/master/SplitLogManager.java