too many files open error due to bonnie.LuceneException

The present indexing process creates 'too many file handles'. When more FHs are needed, it runs out of resources and terminates with an error:

2006-11-13 10:59:11,991 ERROR [confluence.search.lucene.DefaultConfluenceIndexManager] processTasks Failed to refresh the lucene searcher.
java.io.FileNotFoundException: /opt/confluence-data/index/_16oo.f139 (Too many open files)
at java.io.RandomAccessFile.open(Native Method)
at java.io.RandomAccessFile.<init>(RandomAccessFile.java:212)
at org.apache.lucene.store.FSIndexInput$Descriptor.<init>(FSDirectory.java:425)
at org.apache.lucene.store.FSIndexInput.<init>(FSDirectory.java:434)
at org.apache.lucene.store.FSDirectory.openInput(FSDirectory.java:324)
at org.apache.lucene.index.SegmentReader.openNorms(SegmentReader.java:525)
at org.apache.lucene.index.SegmentReader.initialize(SegmentReader.java:157)
at org.apache.lucene.index.SegmentReader.get(SegmentReader.java:129)
at org.apache.lucene.index.SegmentReader.get(SegmentReader.java:115)
at org.apache.lucene.index.IndexReader$1.doBody(IndexReader.java:150)
at org.apache.lucene.store.Lock$With.run(Lock.java:109)
at org.apache.lucene.index.IndexReader.open(IndexReader.java:143)
at org.apache.lucene.index.IndexReader.open(IndexReader.java:138)
at org.apache.lucene.search.IndexSearcher.<init>(IndexSearcher.java:47)
at org.apache.lucene.search.DelayCloseIndexSearcher.<init>(DelayCloseIndexSearcher.java:88)
at org.apache.lucene.search.DateFilterScoringSearcher.<init>(DateFilterScoringSearcher.java:36)
at com.atlassian.confluence.search.lucene.ConfluenceLuceneConnection.createSearcher(ConfluenceLuceneConnection.java:63)
at com.atlassian.confluence.search.lucene.ConfluenceLuceneConnection.refreshSearcher(ConfluenceLuceneConnection.java:102)
at com.atlassian.confluence.search.lucene.DefaultConfluenceIndexManager.processTasks(DefaultConfluenceIndexManager.java:208)
at com.atlassian.confluence.search.lucene.DefaultConfluenceIndexManager.flushQueue(DefaultConfluenceIndexManager.java:93)
at sun.reflect.GeneratedMethodAccessor479.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.springframework.aop.framework.AopProxyUtils.invokeJoinpointUsingReflection(AopProxyUtils.java:61)
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:149)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:116)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:56)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:138)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:152)
at $Proxy15.flushQueue(Unknown Source)
at com.atlassian.confluence.search.lucene.IndexQueueFlusher.executeInternal(IndexQueueFlusher.java:38)
at org.springframework.scheduling.quartz.QuartzJobBean.execute(QuartzJobBean.java:66)
at org.quartz.core.JobRunShell.run(JobRunShell.java:191)
at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:516)