From c6d189dac2ffa4d791bcb2e7bc08d1b9388d89f8 Mon Sep 17 00:00:00 2001
From: "Jeff Washington (jwash)"
 <75863576+jeffwashington@users.noreply.github.com>
Date: Fri, 24 Sep 2021 16:00:41 -0500
Subject: [PATCH] bg threads wait until next expected event (#20126)

---
 runtime/src/bucket_map_holder.rs       |  7 ++++++-
 runtime/src/bucket_map_holder_stats.rs | 11 +++++++++--
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/runtime/src/bucket_map_holder.rs b/runtime/src/bucket_map_holder.rs
index 74c8ed9c91..5853b4d270 100644
--- a/runtime/src/bucket_map_holder.rs
+++ b/runtime/src/bucket_map_holder.rs
@@ -159,9 +159,14 @@ impl<T: IndexValue> BucketMapHolder<T> {
         let flush = self.disk.is_some();
         loop {
             if self.all_buckets_flushed_at_current_age() {
+                let wait = std::cmp::min(
+                    self.age_timer.remaining_until_next_interval(AGE_MS),
+                    self.stats.remaining_until_next_interval(),
+                );
+
                 let mut m = Measure::start("wait");
                 self.wait_dirty_or_aged
-                    .wait_timeout(Duration::from_millis(AGE_MS));
+                    .wait_timeout(Duration::from_millis(wait));
                 m.stop();
                 self.stats
                     .bg_waiting_us
diff --git a/runtime/src/bucket_map_holder_stats.rs b/runtime/src/bucket_map_holder_stats.rs
index da2a1e8981..e26bab35f7 100644
--- a/runtime/src/bucket_map_holder_stats.rs
+++ b/runtime/src/bucket_map_holder_stats.rs
@@ -4,6 +4,9 @@ use solana_sdk::timing::{timestamp, AtomicInterval};
 use std::fmt::Debug;
 use std::sync::atomic::{AtomicU64, AtomicU8, Ordering};
 
+// stats logged every 10 s
+const STATS_INTERVAL_MS: u64 = 10_000;
+
 #[derive(Debug, Default)]
 pub struct BucketMapHolderStats {
     pub get_mem_us: AtomicU64,
@@ -92,9 +95,13 @@ impl BucketMapHolderStats {
         }
     }
 
+    pub fn remaining_until_next_interval(&self) -> u64 {
+        self.last_time
+            .remaining_until_next_interval(STATS_INTERVAL_MS)
+    }
+
     pub fn report_stats<T: IndexValue>(&self, storage: &BucketMapHolder<T>) {
-        // account index stats every 10 s
-        if !self.last_time.should_update(10_000) {
+        if !self.last_time.should_update(STATS_INTERVAL_MS) {
             return;
         }