Comment 3 for bug 241646

Willian,

Check lib/lp/buildmaster/manager.py and you will see that all master xmlrpc calls are executed asynchronously.

IBuilder.slave, which originally is a synchronous python xmlrpc wrapper is overridden with a `RecordingSlave` which later is have its calls dispatched via a twisted xmlrpc.Proxy.

Checking builder availability and collecting builder results are still synchronous.

However this specific bug is about the slave side, which is still performing downloads from librarian synchronously. This is more of issue for chroots, which are 50MB files.