Resolving the last of the selftest thread hangs

[Martin (gzlist)]

On 07/10/2010, Martin Pool <mbp at canonical.com> wrote:
>
> I don't understand how this makes things slower?  Is it because the
> transports never get gc'd, therefore hang around clogging up memory?
> I'm a little surprised the effect is so extreme.

Vincent can correct me on the details here, but basically the fix for
leaking threads is to make sure you join them. However some tests
using socket were getting wedged which was adding the timeout duration
per thread used.

The good news is fixing get_transport really does resolve this
problem, I asked vila to do a run with a hack to fix the hack, and we
went from:

<http://babune.ladeuil.net:24842/job/selftest-windows/190/>
"Took 1 hr 32 min"

To:

<http://babune.ladeuil.net:24842/job/selftest-subset-windows/8/>
"Took 45 min"

So it actually halves the runtime of the full suite on windows on
babune. Apparently also lets OSX actually complete for the first time.

> More broadly than just tests, this seems to indicate that when we get
> a transport, we should perhaps do so within the context of a larger
> scope or context, and then it can be shut down by that.  That might be
> as simple as an ObjectWithCleanups; it goes towards the Context object
> pattern Robert wanted to introduce.  There's more than just tests that
> want to control the way transports are reused or disposed...

This sounds about right to me.

Martin