The call to org.infinispan.loaders.file.FileCacheStore$BufferedFileSync.purge is before org.infinispan.loaders.file.FileCacheStore$BufferedFileSync.write is ever called so there is no mapping from the the path to the FileChannel and it results in the Nullpointer when calling channel.truncate(0);

Hibernate Search: Directory writer-1 06/23 11:15:23 ERROR org.infinispan.interceptors.InvocationContextInterceptor - ISPN00136: Execution error
java.lang.NullPointerException
at org.infinispan.loaders.file.FileCacheStore$BufferedFileSync.purge(FileCacheStore.java:494)
at org.infinispan.loaders.file.FileCacheStore.purgeFile(FileCacheStore.java:382)
at org.infinispan.loaders.file.FileCacheStore.updateBucket(FileCacheStore.java:300)
at org.infinispan.loaders.bucket.BucketBasedCacheStore.storeLockSafe(BucketBasedCacheStore.java:89)
at org.infinispan.loaders.bucket.BucketBasedCacheStore.storeLockSafe(BucketBasedCacheStore.java:49)
at org.infinispan.loaders.LockSupportCacheStore.store(LockSupportCacheStore.java:195)
at org.infinispan.interceptors.CacheStoreInterceptor.visitPutKeyValueCommand(CacheStoreInterceptor.java:211)
at org.infinispan.commands.write.PutKeyValueCommand.acceptVisitor(PutKeyValueCommand.java:77)
at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:119)
at org.infinispan.interceptors.CacheLoaderInterceptor.visitPutKeyValueCommand(CacheLoaderInterceptor.java:82)
at org.infinispan.commands.write.PutKeyValueCommand.acceptVisitor(PutKeyValueCommand.java:77)
at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:119)
at org.infinispan.interceptors.base.CommandInterceptor.handleDefault(CommandInterceptor.java:133)
at org.infinispan.commands.AbstractVisitor.visitPutKeyValueCommand(AbstractVisitor.java:60)
at org.infinispan.commands.write.PutKeyValueCommand.acceptVisitor(PutKeyValueCommand.java:77)
at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:119)
at org.infinispan.interceptors.TxInterceptor.enlistWriteAndInvokeNext(TxInterceptor.java:215)
at org.infinispan.interceptors.TxInterceptor.visitPutKeyValueCommand(TxInterceptor.java:163)
at org.infinispan.commands.write.PutKeyValueCommand.acceptVisitor(PutKeyValueCommand.java:77)
at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:119)
at org.infinispan.interceptors.InvocationContextInterceptor.handleAll(InvocationContextInterceptor.java:99)
at org.infinispan.interceptors.InvocationContextInterceptor.handleDefault(InvocationContextInterceptor.java:64)
at org.infinispan.commands.AbstractVisitor.visitPutKeyValueCommand(AbstractVisitor.java:60)
at org.infinispan.commands.write.PutKeyValueCommand.acceptVisitor(PutKeyValueCommand.java:77)
at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:119)
at org.infinispan.interceptors.BatchingInterceptor.handleDefault(BatchingInterceptor.java:77)
at org.infinispan.commands.AbstractVisitor.visitPutKeyValueCommand(AbstractVisitor.java:60)
at org.infinispan.commands.write.PutKeyValueCommand.acceptVisitor(PutKeyValueCommand.java:77)
at org.infinispan.interceptors.InterceptorChain.invoke(InterceptorChain.java:274)
at org.infinispan.CacheImpl.put(CacheImpl.java:513)
at org.infinispan.CacheSupport.put(CacheSupport.java:51)
at org.infinispan.lucene.FileListOperations.deleteFileName(FileListOperations.java:74)
at org.infinispan.lucene.InfinispanDirectory.deleteFile(InfinispanDirectory.java:229)
at org.apache.lucene.index.IndexFileDeleter.deleteFile(IndexFileDeleter.java:542)
at org.apache.lucene.index.IndexFileDeleter.refresh(IndexFileDeleter.java:341)
at org.apache.lucene.index.DocumentsWriter.flush(DocumentsWriter.java:592)
at org.apache.lucene.index.IndexWriter.doFlush(IndexWriter.java:3331)
at org.apache.lucene.index.IndexWriter.flush(IndexWriter.java:3296)
at org.apache.lucene.index.IndexWriter.prepareCommit(IndexWriter.java:3159)
at org.apache.lucene.index.IndexWriter.commitInternal(IndexWriter.java:3232)
at org.apache.lucene.index.IndexWriter.commit(IndexWriter.java:3214)
at org.apache.lucene.index.IndexWriter.commit(IndexWriter.java:3198)
at org.hibernate.search.backend.Workspace.commitIndexWriter(Workspace.java:220)
at org.hibernate.search.backend.impl.lucene.PerDPQueueProcessor.run(PerDPQueueProcessor.java:109)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:680)