I wish I had another production box to test. But what we and our users see now, actually the users notified our team that the site is suddenly “always loading fast”.. The only change… you guessed it mysqlnd installed. It wasn’t slow before, but people noticed performance degradation at times that the site is most visited when libmysql was used.
After a little hick-up during the first days the server is now running stable with ext/mysql @ mysqlnd. Immediately after the installation of mysqlnd, Miha noticed that persistent connections got closed because of a low
wait_timeout MySQL Server setting. After changing the setting, the problems were gone and all sites (izklop.com, meanduck.com, keintower.de) that are hosted by same hardware setup are running fine.
Based on Miha’s feedback, we started to test persistent connections in more detail (killing server threads, provoking timeouts, checking limits, etc.)…. I must confess that we found and fixed some ten issues around persistent connections which his team had not noticed so far. Meanwhile, however, the persistent connection code seems to have matured very well and does not cause any issues any more neither on izklop.com nor in our testing.
Miha’s statement on the performance did really surprise me. I did not expect to read any such positive feedback. In the past I had many argues with my co-workers on performance. Quite often Andrey told me that in theory mysqlnd should be way faster than libmysql for this or that test. Most of the time I was unable to come up with figures that confirmed our expectations. Therefore, we tried to communicate “give it a try”. So, give it a try…