private void execute() throws ForeignException {

      monitor.rethrowException();

      // running a task (e.g., roll log, flush table) on region server
      taskManager.submitTask(new RSSimpleTask());
      monitor.rethrowException();

      // wait for everything to complete.
      taskManager.waitForOutstandingTasks();
      monitor.rethrowException();

    }
Callable task. TODO. We don't need a thread pool to execute roll log. This can be simplified
with no use of subprocedurepool.
hbase-server/src/test/java/org/apache/hadoop/hbase/procedure/SimpleRSProcedureManager.java