Java Servlet vs PHP

[biswajyoti]

We have to build an online automatic system for evaluating c,c++,java programs for an online programming contest. We feel that the system will be faster if we use a servlet based system rather than a PHP based system though our team is more comfortable with PHP. The database in any case will be MySQL. We feel that a servlet based system can help us pool our database connections and will open up multiple threads rather than processes as in PHP. The system will involve a presentation layer for accepting the files and update the database. When the files get uploaded a system is triggered by RMI to check the files and inserts the scores in the database. A script can periodically update the ranks and create a static page with the ranks. A similar system is also possible in PHP using few system calls. But which is more favourable platform? servlet or php? Is it possible that with one connections in one class I can handle all the db queries in servlet? Is this advisible? Can PHP be used to reduce number of db calls? How can we optimize the system for speed more?