From 6a783fc5c79fc7690de2093fabe5297a58c6bea2 Mon Sep 17 00:00:00 2001
From: Zach <3724288+zedkipp@users.noreply.github.com>
Date: Fri, 20 Feb 2026 16:12:17 -0700
Subject: [PATCH] fix: floor provisioner job queue wait metric (#22184)

After a PostgreSQL round-trip, job timestamps lose their monotonic
clock component, making the subtraction susceptible to wall-clock
adjustments producing a small negative delta. Floor at 1ms since
a zero or negative queue wait is meaningless. Fixes TestProvisionerJobQueueWaitMetric
flakes where small negative values (~ -2ms) are observed.
---
 coderd/provisionerdserver/provisionerdserver.go | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/coderd/provisionerdserver/provisionerdserver.go b/coderd/provisionerdserver/provisionerdserver.go
index 23200bfa89..0e4dd20a05 100644
--- a/coderd/provisionerdserver/provisionerdserver.go
+++ b/coderd/provisionerdserver/provisionerdserver.go
@@ -840,7 +840,11 @@ func (s *server) acquireProtoJob(ctx context.Context, job database.ProvisionerJo
 
 	// Record the time the job spent waiting in the queue.
 	if s.metrics != nil && job.StartedAt.Valid && job.Provisioner.Valid() {
-		queueWaitSeconds := job.StartedAt.Time.Sub(job.CreatedAt).Seconds()
+		// These timestamps lose their monotonic clock component after a Postgres
+		// round-trip, so the subtraction is based purely on wall-clock time. Floor at
+		// 1ms as a defensive measure against clock adjustments producing a negative
+		// delta while acknowledging there's a non-zero queue time.
+		queueWaitSeconds := max(job.StartedAt.Time.Sub(job.CreatedAt).Seconds(), 0.001)
 		s.metrics.ObserveJobQueueWait(string(job.Provisioner), string(job.Type), jobTransition, jobBuildReason, queueWaitSeconds)
 	}