@Override
    public void run() {
      ((LocalRegion) region).getDiskRegion().flushForTesting();
      synchronized (region) {
        region.notify();
        hasBeenNotified = true;
      }
    }
DiskRegOplogRollerWaitingForAsyncWriterJUnitTest: Disk Region test : Oplog Roller should wait
for asynch writer to terminate if asynch flush is going on , before deleting the oplog
geode-core/src/integrationTest/java/org/apache/geode/internal/cache/DiskRegOplogSwtchingAndRollerJUnitTest.java