From 676bacd7299826fb0ea88055d2108f3c6a734291 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bastian=20K=C3=B6cher?= <git@kchr.de>
Date: Mon, 23 Oct 2023 17:06:04 +0200
Subject: [PATCH] Always schedule at least one job onto a core (#1990)

Even if the host configuration is returning `0` for the `lookahead`, we
should schedule at least one job on a core if the core exists.
---
 polkadot/runtime/parachains/src/scheduler.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/polkadot/runtime/parachains/src/scheduler.rs b/polkadot/runtime/parachains/src/scheduler.rs
index af48019124de..f3333d5cf857 100644
--- a/polkadot/runtime/parachains/src/scheduler.rs
+++ b/polkadot/runtime/parachains/src/scheduler.rs
@@ -627,8 +627,8 @@ impl<T: Config> Pallet<T> {
 		if ValidatorGroups::<T>::decode_len().map_or(true, |l| l == 0) {
 			return
 		}
-
-		let n_lookahead = Self::claimqueue_lookahead();
+		// If there exists a core, ensure we schedule at least one job onto it.
+		let n_lookahead = Self::claimqueue_lookahead().max(1);
 		let n_session_cores = T::AssignmentProvider::session_core_count();
 		let cq = ClaimQueue::<T>::get();
 		let ttl = <configuration::Pallet<T>>::config().on_demand_ttl;