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Comment by mattrobenolt | Hacker News Reader

There are frameworks that work like this, iirc. I think some in Scala, but I'm not sure.

IMO, the added complexity wouldn't be worth it with things like Varnish. I think there are better solutions and this is attacking the wrong problem.

But, YRMV. It depends on the situation at hand always.

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Basically anything living in the akka+spray world is written this way. But akka+spray is not an framework in the same sense that django is.

Are there async drivers for e.g. mysql yet? Last time I did that I had a very nice async spray frontend, but it was all backed by a pool of regular blocking threads because that was the only way to use the database driver.

There is this, but it's not particularly mature: https://github.com/mauricio/postgresql-async

I also use https://github.com/etaty/rediscala for accessing redis.

But even without async drivers for MySQL, you can still do:

    val sqlResult: Future[StuffFromSql] = future {
      val stmt = connection.createStatement("...")
      ...
    }

This will tie up a thread, but you can still run other actions in parallel with it.

If you do this, execute the future on a different dispatcher so you aren't blocking the default dispatcher.

This can cause problems if you tie up the default dispatcher with blocking SQL queries while using clustering: the cluster gossip won't be able to fire and if your failure detection settings are low, that node can be marked unreachable by the rest of the cluster.

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