persistent connections are not reliable on cleardb shared plans

Our findings are that persistent connections are inconsistent and should not be used. Sometimes they take 200 milliseconds and other times, they can take up to 19 seconds. In other words, persistent connections are not an auto-fix.

The main problem is that sometimes the persistent connection is lost (ironically). And it spends time looking to re-establish that connection. If it doesn’t find it, it will create a new one, but it spends ~19s doing this dance. So you would see a very slow loading web page (19s+) and will observe “MySQL Server has gone away” in the PHP error logs when this occurs.

persistent connections are not reliable on shared plans