索引时偶尔会遇到FileNotFoundException异常，并不是每次都发生。有人有什么线索吗？这是回溯：
2012-10-14 11:37:28,105 ERROR core.SolrCore - java.io.FileNotFoundException: /home/admin/run/deploy/solr/core_p_shard2/data/index/_cwo.fnm (No such file or directory)
at java.io.RandomAccessFile.open(Native Method)
at java.io.RandomAccessFile.<init>(RandomAccessFile.java:216)
at org.apache.lucene.store.MMapDirectory.openInput(MMapDirectory.java:218)
at org.apache.lucene.store.NRTCachingDirectory.openInput(NRTCachingDirectory.java:232)
at org.apache.lucene.codecs.lucene40.Lucene40FieldInfosReader.read(Lucene40FieldInfosReader.java:47)
at org.apache.lucene.index.SegmentCoreReaders.<init>(SegmentCoreReaders.java:101)
at org.apache.lucene.index.SegmentReader.<init>(SegmentReader.java:55)
at org.apache.lucene.index.ReadersAndLiveDocs.getReader(ReadersAndLiveDocs.java:120)
at org.apache.lucene.index.BufferedDeletesStream.applyDeletes(BufferedDeletesStream.java:267)
at org.apache.lucene.index.IndexWriter.applyAllDeletes(IndexWriter.java:2928)
at org.apache.lucene.index.DocumentsWriter.applyAllDeletes(DocumentsWriter.java:180)
at org.apache.lucene.index.DocumentsWriter.postUpdate(DocumentsWriter.java:310)
at org.apache.lucene.index.DocumentsWriter.updateDocument(DocumentsWriter.java:386)
at org.apache.lucene.index.IndexWriter.updateDocument(IndexWriter.java:1430)
at org.apache.solr.update.DirectUpdateHandler2.addDoc(DirectUpdateHandler2.java:210)
at org.apache.solr.update.processor.RunUpdateProcessor.processAdd(RunUpdateProcessorFactory.java:61)
at org.apache.solr.update.processor.UpdateRequestProcessor.processAdd(UpdateRequestProcessor.java:51)
at org.apache.solr.update.processor.DistributedUpdateProcessor.versionAdd(DistributedUpdateProcessor.java:432)
at org.apache.solr.update.processor.DistributedUpdateProcessor.processAdd(DistributedUpdateProcessor.java:315)
at org.apache.solr.handler.loader.XMLLoader.processUpdate(XMLLoader.java:230)
at org.apache.solr.handler.loader.XMLLoader.load(XMLLoader.java:157)
at org.apache.solr.handler.UpdateRequestHandler$1.load(UpdateRequestHandler.java:92)
at org.apache.solr.handler.ContentStreamHandlerBase.handleRequestBody(ContentStreamHandlerBase.java:74)
at org.apache.solr.handler.RequestHandlerBase.handleRequest(RequestHandlerBase.java:129)
at org.apache.solr.core.SolrCore.execute(SolrCore.java:1656)
at org.apache.solr.servlet.SolrDispatchFilter.execute(SolrDispatchFilter.java:454)
at org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:275)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
除了上述异常，还有一个自动提交错误，这里是详细信息
2012-10-15 01:37:10,722 ERROR update.CommitTracker - auto commit error...:java.io.FileNotFoundException: _5.fdt
at org.apache.lucene.store.FSDirectory.fileLength(FSDirectory.java:266)
at org.apache.lucene.store.NRTCachingDirectory.fileLength(NRTCachingDirectory.java:177)
at org.apache.lucene.index.SegmentInfo.sizeInBytes(SegmentInfo.java:103)
at org.apache.lucene.index.IndexWriter.prepareFlushedSegment(IndexWriter.java:2126)
at org.apache.lucene.index.DocumentsWriter.publishFlushedSegment(DocumentsWriter.java:495)
at org.apache.lucene.index.DocumentsWriter.finishFlush(DocumentsWriter.java:474)
at org.apache.lucene.index.DocumentsWriterFlushQueue$SegmentFlushTicket.publish(DocumentsWriterFlushQueue.java:201)
at org.apache.lucene.index.DocumentsWriterFlushQueue.innerPurge(DocumentsWriterFlushQueue.java:119)
at org.apache.lucene.index.DocumentsWriterFlushQueue.tryPurge(DocumentsWriterFlushQueue.java:148)
at org.apache.lucene.index.DocumentsWriter.doFlush(DocumentsWriter.java:435)
at org.apache.lucene.index.DocumentsWriter.flushAllThreads(DocumentsWriter.java:551)
at org.apache.lucene.index.IndexWriter.prepareCommit(IndexWriter.java:2657)
at org.apache.lucene.index.IndexWriter.commitInternal(IndexWriter.java:2793)
at org.apache.lucene.index.IndexWriter.commit(IndexWriter.java:2773)
at org.apache.solr.update.DirectUpdateHandler2.commit(DirectUpdateHandler2.java:531)
at org.apache.solr.update.CommitTracker.run(CommitTracker.java:214)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:98)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:206)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)
而且我发现索引目录中有很多段，其中大部分是空的，比如 . 索引目录中的文件总数为 35314。
-rw-rw-r-- 1 admin systems 0 Oct 14 11:37 _k3n.fdx
-rw-rw-r-- 1 admin systems 0 Oct 14 11:37 _k3o.fdt
-rw-rw-r-- 1 admin systems 0 Oct 14 11:37 _k3o.fdx
-rw-rw-r-- 1 admin systems 0 Oct 14 11:37 _k3p.fdt
-rw-rw-r-- 1 admin systems 0 Oct 14 11:37 _k3p.fdx
-rw-rw-r-- 1 admin systems 0 Oct 14 11:37 _k3q.fdt
-rw-rw-r-- 1 admin systems 0 Oct 14 11:37 _k3q.fdx
-rw-rw-r-- 1 admin systems 0 Oct 14 11:37 _k3r.fdt
-rw-rw-r-- 1 admin systems 0 Oct 14 11:37 _k3r.fdx
-rw-rw-r-- 1 admin systems 0 Oct 14 11:37 _k3s.fdt
-rw-rw-r-- 1 admin systems 0 Oct 14 11:37 _k3s.fdx
-rw-rw-r-- 1 admin systems 0 Oct 14 11:37 _k3t.fdt
-rw-rw-r-- 1 admin systems 0 Oct 14 11:37 _k3t.fdx
-rw-rw-r-- 1 admin systems 0 Oct 14 11:37 _k3u.fdt
-rw-rw-r-- 1 admin systems 0 Oct 14 11:37 _k3u.fdx
-rw-rw-r-- 1 admin systems 0 Oct 14 11:37 _k3v.fdt
-rw-rw-r-- 1 admin systems 0 Oct 14 11:37 _k3v.fdx
-rw-rw-r-- 1 admin systems 0 Oct 14 11:37 _k3w.fdt
-rw-rw-r-- 1 admin systems 0 Oct 14 11:37 _k3w.fdx
-rw-rw-r-- 1 admin systems 0 Oct 14 11:37 _k3x.fdt
-rw-rw-r-- 1 admin systems 0 Oct 14 11:37 _k3x.fdx
-rw-rw-r-- 1 admin systems 0 Oct 14 11:37 _k3y.fdt
-rw-rw-r-- 1 admin systems 0 Oct 14 11:37 _k3y.fdx
-rw-rw-r-- 1 admin systems 0 Oct 14 11:37 _k3z.fdt
-rw-rw-r-- 1 admin systems 0 Oct 14 11:37 _k3z.fdx
-rw-rw-r-- 1 admin systems 0 Oct 14 11:37 _k40.fdt
-rw-rw-r-- 1 admin systems 0 Oct 14 11:37 _k40.fdx
-rw-rw-r-- 1 admin systems 0 Oct 14 11:37 _k41.fdt
-rw-rw-r-- 1 admin systems 0 Oct 14 11:37 _k41.fdx
-rw-rw-r-- 1 admin systems 0 Oct 14 11:37 _k42.fdt
-rw-rw-r-- 1 admin systems 0 Oct 14 11:37 _k42.fdx