zuul
/
nodepool
Code Issues Proposed changes

Don't update node request in assign handlers loop 

Most of the evaluations that happen in the assignHandlers method
are safe to operate on slightly out-of date node requests.  They
mostly consist of comparing what the request is asking for to what
the provider has available.

The loop iterates over a set of cached node requests which can be
slightly out of date (but not too much) because they are updated
out-of-band by a cache listener.  It's safe for us to make these
comparisons on request data that generally doesn't change over time
any way.  We can greatly speed up the loop by avoiding the explicit
refresh of every request.  If we're a little wrong and we defer
request handling, we'll get it on the next time through the loop.

Later in the loop, we lock the request, and at that point, the lock
routine automatically refreshes the request object in place, so we
know we have current data.

There are a few things we check that can change: the request status,
and the declined worker list(though it's very unlikely to be out of
sync in such a way that it's missing our own name).  We can check
those again after the lock to be sure.

Change-Id: Ib9e16f9e16d05537171b1acb37aa110477495a6e
This commit is contained in:
James E. Blair 2023-03-09 13:09:54 -08:00
parent 3209226fc1
commit fada5d9edf
1 changed files with 5 additions and 4 deletions
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9
nodepool/launcher.py
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@ -156,10 +156,6 @@ class PoolWorker(threading.Thread, stats.StatsReporter):
req_count + 1, len(requests), elapsed)
return False
req = self.zk.getNodeRequest(req.id)
if not req:
continue
# Only interested in unhandled requests
if req.state != zk.REQUESTED:
continue
@ -263,6 +259,11 @@ class PoolWorker(threading.Thread, stats.StatsReporter):
log.debug("Request is in state %s", req.state)
continue
# Skip it if we've already declined
if self.launcher_id in req.declined_by:
log.debug("Request is already declined")
continue
if not reasons_to_decline:
# Got a lock, so assign it
log.info("Assigning node request %s" % req)