Java/JDBC可用的最佳连接池库是什么?

我正在考虑两个主要的候选(免费/开源):

Apache DBCP - http://commons.apache.org/dbcp/ C3P0 - http://sourceforge.net/projects/c3p0

我在博客和其他论坛上读了很多关于他们的文章，但无法做出决定。

有什么相关的替代方案吗?

我使用node-mongodb-native驱动与MongoDB写一个网站。

我有一些关于如何管理连接的问题:

Is it enough using only one MongoDB connection for all requests? Are there any performance issues? If not, can I setup a global connection to use in the whole application? If not, is it good if I open a new connection when request arrives, and close it when handled the request? Is it expensive to open and close a connection? Should I use a global connection pool? I hear the driver has a native connection pool. Is it a good choice? If I use a connection pool, how many connections should be used? Are there other things I should notice?