title: Too many open files while ensure index mongo
body: <p>I would like to create text index on mongo collection. I write </p>
  
  <pre><code>db.test1.ensureIndex({'text':'text'})
  </code></pre>
  
  <p>and then i saw in mongod process</p>
  
  <pre><code>Sun Jan  5 10:08:47.289 [conn1] build index library.test1 { _fts: "text", _ftsx: 1 }
  Sun Jan  5 10:09:00.220 [conn1]         Index: (1/3) External Sort Progress: 200/980    20%
  Sun Jan  5 10:09:13.603 [conn1]         Index: (1/3) External Sort Progress: 400/980    40%
  Sun Jan  5 10:09:26.745 [conn1]         Index: (1/3) External Sort Progress: 600/980    61%
  Sun Jan  5 10:09:37.809 [conn1]         Index: (1/3) External Sort Progress: 800/980    81%
  Sun Jan  5 10:09:49.344 [conn1]      external sort used : 5547 files  in 62 secs
  Sun Jan  5 10:09:49.346 [conn1] Assertion: 16392:FileIterator can't open file: data/_tmp/esort.1388912927.0//file.233errno:24 Too many open files
  </code></pre>
  
  <p>I work on MaxOSX 10.9.1.
  Please help.</p>