ZendSearch opens file handles for all index files and usually keeps them open until the index is closed. On some systems this will lead to a "Too many files open" error. As a result even includes (like including the RuntimeException.php won't work). This happens especially on Sun Solaris machines where you have a more restrictive file handle limit.
File handles should be closed and not be kept open in parallel which will have negative impact on performance for sure. But a slow search engine is better than a search engine that does not work at all.
Hi @mburtscher This repo is not actively maintained if you send a contribution for fix your issue we'll review it.