openstack team mailing list archive

[Johannes Erdfelt <johannes@xxxxxxxxxxx>]

On Wed, Feb 29, 2012, Yun Mao <yunmao@xxxxxxxxx> wrote:
> Thanks for the explanation. Let me see if I understand this.
> 
> 1. Eventlet will never have this problem if there is only 1 OS thread
> -- let's call it main thread.

In fact, that's exactly what Python calls it :)

> 2. In Nova, there is only 1 OS thread unless you use xenapi and/or the
> virt/firewall driver.
> 3. The python logging module uses locks. Because of the monkey patch,
> those locks are actually eventlet or "green" locks and may trigger a
> green thread context switch.
> 
> Based on 1-3, does it make sense to say that in the other OS threads
> (i.e. not main thread), if logging (plus other pure python library
> code involving locking) is never used, and we do not run a eventlet
> hub at all, we should never see this problem?

That should be correct. I'd have to double check all of the monkey
patching that eventlet does to make sure there aren't other cases where
you may inadvertently use eventlet primitives across real threads.

JE