我正在使用嵌入式orientdb服务器运行大型集成测试套件，并在每次测试后进行清理。但是，在某些时候测试失败是由于某些fts索引已被删除而另一个尝试访问它们。结果我收到了：
Exception in thread "Thread-11" java.lang.RuntimeException: java.io.FileNotFoundException: _2.fdt
at org.apache.lucene.search.ControlledRealTimeReopenThread.run(ControlledRealTimeReopenThread.java:247)
Caused by: java.io.FileNotFoundException: _2.fdt
at org.apache.lucene.store.FSDirectory.fileLength(FSDirectory.java:261)
at org.apache.lucene.index.SegmentCommitInfo.sizeInBytes(SegmentCommitInfo.java:141)
at org.apache.lucene.index.DocumentsWriterPerThread.sealFlushedSegment(DocumentsWriterPerThread.java:529)
at org.apache.lucene.index.DocumentsWriterPerThread.flush(DocumentsWriterPerThread.java:502)
at org.apache.lucene.index.DocumentsWriter.doFlush(DocumentsWriter.java:506)
at org.apache.lucene.index.DocumentsWriter.flushAllThreads(DocumentsWriter.java:616)
at org.apache.lucene.index.IndexWriter.getReader(IndexWriter.java:370)
at org.apache.lucene.index.StandardDirectoryReader.doOpenFromWriter(StandardDirectoryReader.java:288)
at org.apache.lucene.index.StandardDirectoryReader.doOpenIfChanged(StandardDirectoryReader.java:263)
at org.apache.lucene.index.StandardDirectoryReader.doOpenIfChanged(StandardDirectoryReader.java:253)
at org.apache.lucene.index.DirectoryReader.openIfChanged(DirectoryReader.java:170)
at org.apache.lucene.search.SearcherManager.refreshIfNeeded(SearcherManager.java:118)
at org.apache.lucene.search.SearcherManager.refreshIfNeeded(SearcherManager.java:58)
at org.apache.lucene.search.ReferenceManager.doMaybeRefresh(ReferenceManager.java:176)
at org.apache.lucene.search.ReferenceManager.maybeRefreshBlocking(ReferenceManager.java:253)
at org.apache.lucene.search.ControlledRealTimeReopenThread.run(ControlledRealTimeReopenThread.java:245)
任何人都知道如何解决这个问题？