There are quite a few questions regarding how file descriptors get handled when processes are forked.
Remember that fork() makes a copy of the program, which means all descriptors are copied. Unfortunately, this is a rather bad situation for a PHP program because most descriptors are handled by PHP or a PHP Extension internally.
The simple, and probably "proper" way to solve this issue is to fork before hand, there really should be no need to fork at many different points among a program, you would simply fork, and then delegate the work. Use a master/worker hierarchy.
For example, if you need to have many processes that use a MySQL Connection, just fork before the connection is made, that way each child has it´s own connection to mysql that it, and it alone, manages.
With careful and correct usage, fork() can be an extremely powerful tool.
--Please remember to take proper care of your children.
