From 2d78f8ad2ad29d36a7045d093dfd74b3c7bdb8ab Mon Sep 17 00:00:00 2001
From: "Jeff Washington (jwash)"
 <75863576+jeffwashington@users.noreply.github.com>
Date: Mon, 4 Oct 2021 19:20:10 -0400
Subject: [PATCH] parallelize unref_from_storage from
 clean_dead_slots_from_accounts_index (#20411)

---
 runtime/src/accounts_db.rs | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/runtime/src/accounts_db.rs b/runtime/src/accounts_db.rs
index b7fbdd1db1..2540fca327 100644
--- a/runtime/src/accounts_db.rs
+++ b/runtime/src/accounts_db.rs
@@ -5804,12 +5804,23 @@ impl AccountsDb {
         purged_stored_account_slots: Option<&mut AccountSlots>,
     ) {
         if let Some(purged_stored_account_slots) = purged_stored_account_slots {
+            let len = purged_stored_account_slots.len();
+            // we could build a higher level function in accounts_index to group by bin
+            const BATCH_SIZE: usize = 10_000;
+            let batches = 1 + (len / BATCH_SIZE);
+            self.thread_pool_clean.install(|| {
+                (0..batches).into_par_iter().for_each(|batch| {
+                    let skip = batch * BATCH_SIZE;
+                    for (_slot, pubkey) in purged_slot_pubkeys.iter().skip(skip).take(BATCH_SIZE) {
+                        self.accounts_index.unref_from_storage(pubkey);
+                    }
+                })
+            });
             for (slot, pubkey) in purged_slot_pubkeys {
                 purged_stored_account_slots
                     .entry(pubkey)
                     .or_default()
                     .insert(slot);
-                self.accounts_index.unref_from_storage(&pubkey);
             }
         }