public void forceFlush() {
    try {
      flushFlusher(false);
    } catch (InterruptedException ie) {
      Thread.currentThread().interrupt();
      getCache().getCancelCriterion().checkCancelInProgress(ie);
    }
  }
force a flush but do it async (don't wait for the flush to complete).
geode-core/src/main/java/org/apache/geode/internal/cache/DiskStoreImpl.java