[GitHub] [spark] melin commented on issue #24672: [SPARK-27801][SQL] Improve performance of InMemoryFileIndex.listLeafFiles for HDFS directories with many files

[GitBox <gi...@apache.org>]

melin commented on issue #24672: [SPARK-27801][SQL] Improve performance of InMemoryFileIndex.listLeafFiles for HDFS directories with many files
URL: https://github.com/apache/spark/pull/24672#issuecomment-495970900
 
 
   ```
   @RequestMapping(value = "v1/hdfsPref", produces = "text/plain;charset=UTF-8")
       @ResponseBody
       public String hdfsPref(String path) throws Exception {
           DataCenter dataCenter = new DataCenter("hangzhou", "杭州");
           UserGroupInformation userGroupInformation = confLoader.loginUserFromKeytab(dataCenter);
           return userGroupInformation.doAs(new PrivilegedExceptionAction<String>() {
   
               @Override
               public String run() throws Exception {
                   FileSystem fileSystem = confLoader.getFileSystem(dataCenter);
                   org.apache.hadoop.fs.Path filePath = new org.apache.hadoop.fs.Path(path);
   
                   Stopwatch stopwatch = Stopwatch.createStarted();
                   FileStatus[] fileStatuses = fileSystem.listStatus(filePath);
                   stopwatch.stop();
                   String msg = "listStatus: " + fileStatuses.length + ", times: " + stopwatch.elapsed(TimeUnit.MILLISECONDS) + "ms";
   
                   stopwatch.reset().start();
                   RemoteIterator<LocatedFileStatus> remoteIter = fileSystem.listLocatedStatus(filePath);
                   List<LocatedFileStatus> myList = Lists.newArrayList();
                   while (remoteIter.hasNext()) {
                       myList.add(remoteIter.next());
                   }
   
                   stopwatch.stop();
                   msg += "\nlistLocatedStatus: " + myList.size() + ", times: " + stopwatch.elapsed(TimeUnit.MILLISECONDS) + "ms";
   
                   return msg;
               }
           });
       }
   
   test data:
   listStatus: 8001, times: 114ms
   listLocatedStatus: 8001, times: 807ms
   ```

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