void forceRolling(DiskRegion dr) {
    if (getOplogSet().getChild() == this) {
      getParent().getBackupLock().lock();
      try {
        synchronized (lock) {
          if (getOplogSet().getChild() == this) {
            switchOpLog(dr, 0, null);
          }
        }
      } finally {
        getParent().getBackupLock().unlock();
      }
      if (LocalRegion.ISSUE_CALLBACKS_TO_CACHE_OBSERVER) {
        CacheObserverHolder.getInstance().afterSwitchingOplog();
      }
    }
  }
This oplog will be forced to switch to a new oplog
geode-core/src/main/java/org/apache/geode/internal/cache/Oplog.java