default AsyncBufferedMutatorBuilder disableWriteBufferPeriodicFlush() {
    return setWriteBufferPeriodicFlush(0, TimeUnit.NANOSECONDS);
  }
Disable the periodical flush, i.e, set the timeout to 0.
hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncBufferedMutatorBuilder.java