AcctIdx: hold ranges in memory uses multiple threads (#22031)

runtime/src/accounts_index.rs

@@ -13,6 +13,10 @@ use {
     log::*,
     ouroboros::self_referencing,
     rand::{thread_rng, Rng},
+    rayon::{
+        iter::{IntoParallelIterator, ParallelIterator},
+        ThreadPool,
+    },
     solana_measure::measure::Measure,
     solana_sdk::{
         clock::{BankId, Slot},
@@ -742,21 +746,22 @@ impl<'a, T: IndexValue> AccountsIndexIterator<'a, T> {
         }
     }
 
-    pub fn hold_range_in_memory<R>(&self, range: &R, start_holding: bool)
+    pub fn hold_range_in_memory<R>(&self, range: &R, start_holding: bool, thread_pool: &ThreadPool)
     where
-        R: RangeBounds<Pubkey> + Debug,
+        R: RangeBounds<Pubkey> + Debug + Sync,
     {
         // forward this hold request ONLY to the bins which contain keys in the specified range
         let (start_bin, bin_range) = self.bin_start_and_range();
-        self.account_maps
-            .iter()
-            .skip(start_bin)
-            .take(bin_range)
-            .for_each(|map| {
+        // the idea is this range shouldn't be more than a few buckets, but the process of loading from disk buckets is very slow
+        // so, parallelize the bucket loads
+        thread_pool.install(|| {
+            (0..bin_range).into_par_iter().for_each(|idx| {
+                let map = &self.account_maps[idx + start_bin];
                 map.read()
                     .unwrap()
                     .hold_range_in_memory(range, start_holding);
             });
+        });
     }
 }
 
@@ -1460,12 +1465,12 @@ impl<T: IndexValue> AccountsIndex<T> {
         rv.map(|index| slice.len() - 1 - index)
     }
 
-    pub fn hold_range_in_memory<R>(&self, range: &R, start_holding: bool)
+    pub fn hold_range_in_memory<R>(&self, range: &R, start_holding: bool, thread_pool: &ThreadPool)
     where
-        R: RangeBounds<Pubkey> + Debug,
+        R: RangeBounds<Pubkey> + Debug + Sync,
     {
         let iter = self.iter(Some(range), true);
-        iter.hold_range_in_memory(range, start_holding);
+        iter.hold_range_in_memory(range, start_holding, thread_pool);
     }
 
     pub fn set_startup(&self, value: bool) {