As said on http://www.scala-lang.org/api/2.11.7/index.html#scala.concurrent.ExecutionContext http://www.scala-lang.org/api/2.11.7/index.html#scala.concur... the

As said on http://www.scala-lang.org/api/2.11.7/index.html#scala.concurrent.ExecutionContext http://www.scala-lang.org/api/2.11.7/index.html#scala.concur... the default global should not be imported all over the place. It's better to declare functions with an implicit ExecutionContext and try to declare your execution contexts in a few well-known places. The (web) app I'm working on uses several ExecutionContexts (database access has a specific one for example.)