On Monday, August 29, 2016 1:04:58 PM CEST Michal Novotny wrote:
On Fri, Aug 26, 2016 at 6:22 PM, Pavel Raiskup
> Does it spawn builders even if there is no build queue yet?
Yes, it does. I completely cut off our backend dev instance from frontend
and repeated the fresh-start experiment.
This time the build queue was empty for sure and the builders were still
being spawned. I also confirmed in the
code that it should be so. These parts (around VmMaster ) weren't touched.
I've done a quick review of the patch now, and I pretty much like the
backend's "take-one-task" only approach. That way you can control the
queue on frontend (with atomicity given by PostgreSQL), while still that
is 'pull down' approach from backend.
There is one drawback, however -- the ugly workaround DEFER_BUILD_SECONDS.
The problem is that you now put all builds (all architectures) into one
build queue (that has "starving" consequences if you wasn't using
I would suggest you to add one additional argument into /backend/waiting/
backend API -> requested architecture.
* Then, you can remove everything related to "defer" action both on BE
* You can lower the BE<->FE traffic, and significantly lower IO on
front-end --> because then you can first allocate appropriate VM, and
right after that assign job (not vice versa: take job, then try to
take VM and possibly defer the job).
Also, the 'take-build' (load_job() in particular) method should be
automatically move the action into 'running' state, and completely remove the
"starting" state, which has zero informational value anyway (users know/should
know the build queue priority anyway).
* Then we could much easily implement "multiple-backends"
support, I wanted to have something like this for a long time.