In a matter of minutes, and without being able to gather data to understand what might be behind it, I get the following error:

  

RecursiveDirectoryIterator :: __ construct (path / to / directory) [recursivedirectoryiterator .-- construct]: failed to open dir: Too many open files

The server where this error occurs is running Apache / 2.2.24 and PHP / 5.3.22.

$workingPath = "caminho/para/directoria";

$iterator = new RecursiveIteratorIterator(
    new RecursiveDirectoryIterator($workingPath),
    RecursiveIteratorIterator::SELF_FIRST
);

$files = iterator_to_array($iterator, true); /* tentativa de abafar o erro
                                                como sugerido num tópico do SOEN
                                                mas sem sucesso em resolver a questão */

foreach ($files as $file) {
  // código a executar por cada ficheiro localizado
}

Question

How can I correctly evaluate the cause of this error and / or find out if there are any limits that I do not know could be causing the same?