From c616c348258703464de00e41bb506669f110b9f2 Mon Sep 17 00:00:00 2001
From: Ryo Onodera <ryoqun@gmail.com>
Date: Mon, 10 May 2021 22:44:46 +0900
Subject: [PATCH] Add comment for another unspoken eager collection subtlety
 (#17137)

---
 runtime/src/bank.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/runtime/src/bank.rs b/runtime/src/bank.rs
index 298d5846f1..575e88dd80 100644
--- a/runtime/src/bank.rs
+++ b/runtime/src/bank.rs
@@ -3568,6 +3568,9 @@ impl Bank {
                 .collect_from_existing_account(&pubkey, &mut account);
             // Store all of them unconditionally to purge old AppendVec,
             // even if collected rent is 0 (= not updated).
+            // Also, there's another subtle side-effect from this: this
+            // ensures we verify the whole on-chain state (= all accounts)
+            // via the account delta hash slowly once per an epoch.
             self.store_account(&pubkey, &account);
         }
         self.collected_rent.fetch_add(rent, Relaxed);