private void doRun() throws IOException {
      LOG.trace("Writer thread starting");
      while (true) {
        EntryBuffers.RegionEntryBuffer buffer = entryBuffers.getChunkToWrite();
        if (buffer == null) {
          // No data currently available, wait on some more to show up
          synchronized (controller.dataAvailable) {
            if (shouldStop) {
              return;
            }
            try {
              controller.dataAvailable.wait(500);
            } catch (InterruptedException ie) {
              if (!shouldStop) {
                throw new RuntimeException(ie);
              }
            }
          }
          continue;
        }

        assert buffer != null;
        try {
          writeBuffer(buffer);
        } finally {
          entryBuffers.doneWriting(buffer);
        }
      }
    }
Set status message in {@link MonitoredTask} instance that is set in this OutputSink
@param msg message to update the status with
hbase-server/src/main/java/org/apache/hadoop/hbase/wal/OutputSink.java