So, when you connect on the fly to a database your subject to a variety of issues, like when the db is not available and when the db does not have a route.
One of the main reasons why a dev may want to connect on the fly is because they have too many front ends to hold a persistent connection on the backends. Since mySQL does not use libevent, holding open threads to mySQL is much more costly. Threads == Memory.
But, that's here nor there. The main purpose of this post is to talk about how to recover from failed connections that block apache threads.
Common Failures: No route to Host Flapping NIC Locked Tables Recovering from a Crash more of the same.
My Environment: I have a bunch of webservers (200+) that all have 300 possible threads (60000 possible connections to a single DB) behind a load [Read more...]
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