fix deadlock

core/src/replay_stage.rs

@@ -3859,6 +3859,7 @@ impl ReplayStage {
         epoch_slots_frozen_slots: &mut EpochSlotsFrozenSlots,
         drop_bank_sender: &Sender<Vec<Arc<Bank>>>,
     ) {
+        bank_forks.read().unwrap().prune_program_cache(new_root);
         let removed_banks = bank_forks.write().unwrap().set_root(
             new_root,
             accounts_background_request_sender,

ledger/src/blockstore_processor.rs

@@ -1555,6 +1555,11 @@ fn load_frozen_forks(
                 root = new_root_bank.slot();
 
                 leader_schedule_cache.set_root(new_root_bank);
+                new_root_bank
+                    .loaded_programs_cache
+                    .write()
+                    .unwrap()
+                    .prune(root, new_root_bank.epoch());
                 let _ = bank_forks.write().unwrap().set_root(
                     root,
                     accounts_background_request_sender,

runtime/src/bank_forks.rs

@@ -405,22 +405,23 @@ impl BankForks {
         )
     }
 
+    pub fn prune_program_cache(&self, root: Slot) {
+        self.banks.get(&root).map(|root_bank| {
+            root_bank
+                .loaded_programs_cache
+                .write()
+                .unwrap()
+                .prune(root, root_bank.epoch());
+        });
+    }
+
     pub fn set_root(
         &mut self,
         root: Slot,
         accounts_background_request_sender: &AbsRequestSender,
         highest_super_majority_root: Option<Slot>,
     ) -> Vec<Arc<Bank>> {
         let program_cache_prune_start = Instant::now();
-        let root_bank = self
-            .banks
-            .get(&root)
-            .expect("root bank didn't exist in bank_forks");
-        root_bank
-            .loaded_programs_cache
-            .write()
-            .unwrap()
-            .prune(root, root_bank.epoch());
         let set_root_start = Instant::now();
         let (removed_banks, set_root_metrics) = self.do_set_root_return_metrics(
             root,