Feature request: Minimum connections

[rdrey]

I currently instantiate my pool like this:

class EPPPool(ConnectionPool):
    def _new_connection(self):
        try:
            return EPPSession(self.config)
        except Exception as e:
            # If the pool fails to start or gets too small, quit
            if len(self.conn) < self.size / 2:
                logging.error("Pool unhealthy, quitting")
                os.kill(os.getpid(), signal.SIGTERM)
            raise e

this works fine, but technically I'd like the pool to die while it's getting constructed (and not asynchronously).

I would like to propose a minimum_size, which gets created synchronously in
ConnectionPool.__init__. The minimum number of connections could be created immediately (self._addOne()) and the constructor would raise an exception if creating them fails, then the remaining size - minimum_size connections get created as usual (gevent.spawn_later(self.SPAWN_FREQUENCY*i, self._addOne)).

How do you feel about this change? It's pretty small and restricted to ConnectionPool.__init__.

Thanks, great little module!