From 38d306114392264918a4af8d863391879eabcb47 Mon Sep 17 00:00:00 2001
From: Christian Schwarz <christian@neon.tech>
Date: Tue, 28 Mar 2023 11:32:21 +0200
Subject: [PATCH] add comment on not-need to be 100% accurate about
 max_layer_size

---
 pageserver/src/disk_usage_eviction_task.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/pageserver/src/disk_usage_eviction_task.rs b/pageserver/src/disk_usage_eviction_task.rs
index c0ee42066b..719e69000f 100644
--- a/pageserver/src/disk_usage_eviction_task.rs
+++ b/pageserver/src/disk_usage_eviction_task.rs
@@ -506,6 +506,10 @@ async fn extend_lru_candidates(
         return ControlFlow::Break(());
     }
 
+    // If one of the timelines becomes `!is_active()` during the iteration,
+    // for example because we're shutting down, then `max_layer_size` can be too small.
+    // That's OK. This code only runs under a disk pressure situation, and being
+    // a little unfair to tenants during shutdown in such a situation is tolerable.
     let mut max_layer_size: Option<u64> = None;
     for tl in tenant.list_timelines() {
         if !tl.is_active() {