From: Michael Tremer <michael.tremer@ipfire.org>
Date: Fri, 5 May 2023 14:21:06 +0000 (+0000)
Subject: builders: Improve autoscale algorithm
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f447be0049beeccb1d96d3b2f98f5f5a9197b6b6;p=pbs.git

builders: Improve autoscale algorithm

We will try to avoid starting any builders that are currently shut down.

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>
---

diff --git a/src/buildservice/builders.py b/src/buildservice/builders.py
index f709e811..46a2eb52 100644
--- a/src/buildservice/builders.py
+++ b/src/buildservice/builders.py
@@ -96,13 +96,18 @@ class Builders(base.Object):
 		# XXX max queue length
 		threshold = datetime.timedelta(minutes=5)
 
-		# Fetch all enabled builders and whether they are running or not
-		builders = {
-			builder : await builder.is_running() for builder in self if builder.enabled
-		}
+		# Fetch all enabled builders
+		builders = [b for b in self if b.enabled]
+
+		# Fetch the priority for each builder
+		builders = dict(
+			zip(builders, await asyncio.gather(
+				*(b._autoscale_sort() for b in builders),
+			)),
+		)
 
-		# Sort all running builders to the beginning of the list
-		builders = sorted(builders, key=lambda b: (builders[b], b))
+		# Sort all builders after their priority
+		builders = sorted(builders, key=lambda b: (-builders[b], b))
 
 		# Store the length of the queue for each builder
 		queue = {
@@ -676,6 +681,28 @@ class Builder(base.DataObject):
 
 		log.debug("%s has been stopped" % self)
 
+	async def _autoscale_sort(self):
+		"""
+			This function returns a number that tells the autoscaling algorithm
+			in which order a builder should be considered.
+
+			The higher the number, the sooner the builder is considered.
+		"""
+		# Return something neutral if this isn't an AWS instance
+		if not self.instance:
+			return 0
+
+		# Running builds should come first
+		if await self.is_running():
+			return 1
+
+		# Put builders that are shutting down at the end
+		elif await self.is_shutting_down():
+			return -1
+
+		# Otherwise return a neutral preference
+		return 0
+
 	# Stats
 
 	@lazy_property