Prepare mysql statements on other connections if the connections where it's already prepared are busy

[bwoebi]

To avoid bigger latencies when multiple prepared statements are prepared on a same connection and they're all executed simultaneously.

[And not just when connections crashed.]

[kelunik]

@trowski Is this already been solved? IIRC, there have been changes to implement this, no? Currently the client falls over in case of many concurrent executions of a single prepared statement.