v1.17: ancient shrink on its own cadence (backport of #33712)

accounts-db/src/accounts_db.rs

@@ -4395,11 +4395,12 @@ impl AccountsDb {
 
     /// get a sorted list of slots older than an epoch
     /// squash those slots into ancient append vecs
-    fn shrink_ancient_slots(&self, oldest_non_ancient_slot: Slot) {
+    pub fn shrink_ancient_slots(&self, epoch_schedule: &EpochSchedule) {
         if self.ancient_append_vec_offset.is_none() {
             return;
         }
 
+        let oldest_non_ancient_slot = self.get_oldest_non_ancient_slot(epoch_schedule);
         let can_randomly_shrink = true;
         let sorted_slots = self.get_sorted_potential_ancient_slots(oldest_non_ancient_slot);
         if self.create_ancient_storage == CreateAncientStorage::Append {
@@ -4744,10 +4745,6 @@ impl AccountsDb {
 
     pub fn shrink_candidate_slots(&self, epoch_schedule: &EpochSchedule) -> usize {
         let oldest_non_ancient_slot = self.get_oldest_non_ancient_slot(epoch_schedule);
-        if !self.shrink_candidate_slots.lock().unwrap().is_empty() {
-            // this can affect 'shrink_candidate_slots', so don't 'take' it until after this completes
-            self.shrink_ancient_slots(oldest_non_ancient_slot);
-        }
 
         let shrink_candidates_slots =
             std::mem::take(&mut *self.shrink_candidate_slots.lock().unwrap());

runtime/src/accounts_background_service.rs

@@ -21,7 +21,7 @@ use {
     solana_accounts_db::{
         accounts_db::CalcAccountsHashDataSource, accounts_hash::CalcAccountsHashConfig,
     },
-    solana_measure::measure::Measure,
+    solana_measure::{measure::Measure, measure_us},
     solana_sdk::clock::{BankId, Slot},
     stats::StatsManager,
     std::{
@@ -383,6 +383,8 @@ impl SnapshotRequestHandler {
         snapshot_root_bank.clean_accounts(*last_full_snapshot_slot);
         clean_time.stop();
 
+        let (_, shrink_ancient_time_us) = measure_us!(snapshot_root_bank.shrink_ancient_slots());
+
         let mut shrink_time = Measure::start("shrink_time");
         snapshot_root_bank.shrink_candidate_slots();
         shrink_time.stop();
@@ -464,6 +466,7 @@ impl SnapshotRequestHandler {
             ("snapshot_time", snapshot_time.as_us(), i64),
             ("total_us", total_time.as_us(), i64),
             ("non_snapshot_time_us", non_snapshot_time_us, i64),
+            ("shrink_ancient_time_us", shrink_ancient_time_us, i64),
         );
         Ok(snapshot_root_bank.block_height())
     }
@@ -705,6 +708,7 @@ impl AccountsBackgroundService {
                             bank.force_flush_accounts_cache();
                             bank.clean_accounts(last_full_snapshot_slot);
                             last_cleaned_block_height = bank.block_height();
+                            bank.shrink_ancient_slots();
                         }
                         bank.shrink_candidate_slots();
                     }

runtime/src/bank.rs

@@ -7817,6 +7817,13 @@ impl Bank {
             .shrink_candidate_slots(self.epoch_schedule())
     }
 
+    pub(crate) fn shrink_ancient_slots(&self) {
+        self.rc
+            .accounts
+            .accounts_db
+            .shrink_ancient_slots(self.epoch_schedule())
+    }
+
     pub fn no_overflow_rent_distribution_enabled(&self) -> bool {
         self.feature_set
             .is_active(&feature_set::no_overflow_rent_distribution::id())