I get some errors on the MongoDB side, the error complains that it has reached the maximum allowable connections.
Surprise if in any case it is necessary to increase the maximum number of allowed connections.
Check out the MongoDB documentation:
http://www.mongodb.org/
use this command line argument:
--maxConns arg max number of simultaneous connections
You can check this: http://blog.boxedice.com/2011/06/08/mongodb-connection-overhead/