通过c3p0在mysql中查询超时

Question

I am using c3p0 as connection pooling and ebean as ORM implementation. Currently i am setting below properties in c3p0 pool:

minPoolSize
maxPoolSize
maxIdleTime
preferredTestQuery

But i was wandering how to set a timeout on the query ie suppose if the query take more than 200 milisec then just give up rather than waiting on it infinitely. How would you achieve this via c3p0. I know how to set this by plain JDBC ie Statement.setQueryTimeout() but how to do the same via c3p0. Or is there any other way?

is maxIdleTime and query timeout that i have mentioned does the same thing ie after certain period of time if we dont get the response kill the connection? Thanks in advance.

Answer 1

No, maxIdleTime has nothing to do with how long a query can run. It defines how long Connections will be allowed to sit idle in the pool before they will expire and be destroyed.

c3p0 is plain JDBC. Per the JDBC spec, it offers transparent Connection pooling. Transparent means in this context that the API doesn't change, your code should be basically the same with or without the pool. You are welcome to call Statement.setQueryTimeout() on Statements derived from a c3p0-managed Connection as you would with any other Statement.

In general, c3p0 doesn't interfere with Connections while they are checked out. Once a client application is using a Connection, c3p0 observes but does not much mess with what the client app does. The main exception to this is the config param unreturnedConnectionTimeout , which is intended to help debug or workaround Connection leaks. [See here ] In a real pinch, you could use unreturnedConnectionTimeout to do what you want, force abandonment of slower queries, albeit in a rather brutal way. unreturnedConnectionTimeout will force the unreturned Connection to be close()ed after the set period of time, and the pool will usually have to acquire a replacement. I'd start with Statement.setQueryTimeout before trying `unreturnedConnectionTimeout', though.