Слишком много открытых файлов с помощью child_process

I get the following error only on my Rackspace Ubuntu Maverick instance...but not on my local Ubuntu Lucid VM:

pipe(): Too many open files
pipe(): Too many open files

child_process.js:223
  var fds = this._internal.spawn(path,
                           ^
Error: Error spawning
    at ChildProcess.spawn (child_process.js:223:28)
    at child_process.js:10:15
    etc..etc..

The code that generates it:

function getHeader(url, callback)
{
  var client = spawn('curl', ['-I', url]);
  client.stdout.on('data', function(data)
  {
    client.kill('SIGTERM');
    callback(data.toString('utf8'));
  });
}