title: About saving a model file in spark
body: <p>I'm testing codes of Linear Support Vector Machines (SVMs) in below link: </p>
  
  <p><a href="http://spark.apache.org/docs/latest/mllib-linear-methods.html#linear-support-vector-machines-svms" rel="nofollow">http://spark.apache.org/docs/latest/mllib-linear-methods.html#linear-support-vector-machines-svms</a></p>
  
  <p>I tested code with <code>spark-shell --master spark://192.168.0.181:7077</code>. </p>
  
  <p>I modified last 2 lines like this: </p>
  
  <pre><code>model.save(sc, "file:///Apps/spark/data/mllib/testModelPath") 
  val sameModel = SVMModel.load(sc, "file:///Apps/spark/data/mllib/testModelPath")
  </code></pre>
  
  <p>model.save ended with no error but when I tried to load that model it gives following message: 
  INFO mapred.FileInputFormat: Total input paths to process : 0 
  java.lang.UnsupportedOperationException: empty collection 
  : 
  : </p>
  
  <p>When I tested without <code>file:///</code> , model saved to HDFS system, and I can load that model without error. </p>
  
  <pre><code>hadoop@XXX /Apps/spark/data/mllib/testModelPath/data&gt; ll 
  
  drwxrwxr-x 2 hadoop hadoop 4096 2015-10-07 16:47 ./ 
  drwxrwxr-x 4 hadoop hadoop 4096 2015-10-07 16:47 ../ 
  -rw-rw-r-- 1 hadoop hadoop    8 2015-10-07 16:47 ._SUCCESS.crc 
  -rw-rw-r-- 1 hadoop hadoop   16 2015-10-07 16:47 ._common_metadata.crc 
  -rw-r--r-- 1 hadoop hadoop    0 2015-10-07 16:47 _SUCCESS 
  -rw-r--r-- 1 hadoop hadoop  932 2015-10-07 16:47 _common_metadata 
  </code></pre>
  
  <p>When I checked the folder after model saving, I found _metadata file is not created. </p>
  
  <p>Dose anyone know the reason of this?</p>