title: Why java FileOutputStream's write() or flush() doesn't make NFS client really send data to NFS server?
body: <p>My Java web application use NFS file system, I use FileOutputStream to open, write multiple chunks and then close the file.</p>
  
  <p>From the profiler stats I found that stream.write(byte[] payload,int begin, int length) and even stream.flush() takes zero milliseconds. Only the method call  stream.close() takes non-zero milliseconds.</p>
  
  <p>It seems that java FileOutputStream's write() or flush() doesn't really cause NFS client to send data to NFS server.  Is there any other Java class will make NFS client flush data in real time? or there is some NFS client tuning need to be done?</p>