From 499b4f7ebaa16d412554886de99ac33540d99fe0 Mon Sep 17 00:00:00 2001
From: Konstantin Knizhnik <knizhnik@garret.ru>
Date: Fri, 23 Apr 2021 18:02:58 +0300
Subject: [PATCH] Log garbage collection statistics

---
 pageserver/src/bin/pageserver.rs | 8 +++-----
 pageserver/src/page_cache.rs     | 9 +++++++--
 2 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/pageserver/src/bin/pageserver.rs b/pageserver/src/bin/pageserver.rs
index 5a0c7ab502..3d9cc9b891 100644
--- a/pageserver/src/bin/pageserver.rs
+++ b/pageserver/src/bin/pageserver.rs
@@ -19,8 +19,8 @@ use slog::Drain;
 
 use pageserver::{page_service, tui, zenith_repo_dir, PageServerConf};
 
-const DEFAULT_GC_HORIZON: u64 = 64 * 1024 * 1024;
-const DEFAULT_GC_PERIOD_SEC: u64 = 10;
+const DEFAULT_GC_HORIZON: u64 = 1024 * 1024 * 1024;
+const DEFAULT_GC_PERIOD_SEC: u64 = 600;
 
 fn main() -> Result<()> {
     let arg_matches = App::new("Zenith page server")
@@ -213,7 +213,7 @@ fn init_logging(conf: &PageServerConf) -> Result<slog_scope::GlobalLoggerGuard,
         let decorator = slog_term::PlainSyncDecorator::new(log_file);
         let drain = slog_term::CompactFormat::new(decorator).build();
         let drain = slog::Filter::new(drain, |record: &slog::Record| {
-            if record.level().is_at_least(slog::Level::Debug) {
+            if record.level().is_at_least(slog::Level::Info) {
                 return true;
             }
             false
@@ -229,13 +229,11 @@ fn init_logging(conf: &PageServerConf) -> Result<slog_scope::GlobalLoggerGuard,
             if record.level().is_at_least(slog::Level::Info) {
                 return true;
             }
-            /* let's do not be too verbose
             if record.level().is_at_least(slog::Level::Debug)
                 && record.module().starts_with("pageserver")
             {
                 return true;
             }
-            */
             false
         })
         .fuse();
diff --git a/pageserver/src/page_cache.rs b/pageserver/src/page_cache.rs
index 8e9b9a081b..8060b385f1 100644
--- a/pageserver/src/page_cache.rs
+++ b/pageserver/src/page_cache.rs
@@ -21,7 +21,7 @@ use std::sync::atomic::AtomicU64;
 use std::sync::atomic::Ordering;
 use std::sync::{Arc, Condvar, Mutex};
 use std::thread;
-use std::time::Duration;
+use std::time::{Duration, Instant};
 use std::{convert::TryInto, ops::AddAssign};
 use zenith_utils::seqwait::SeqWait;
 
@@ -122,7 +122,6 @@ pub fn get_or_restore_pagecache(
     timelineid: ZTimelineId,
 ) -> anyhow::Result<Arc<PageCache>> {
     let mut pcaches = PAGECACHES.lock().unwrap();
-
     match pcaches.get(&timelineid) {
         Some(pcache) => Ok(pcache.clone()),
         None => {
@@ -403,6 +402,9 @@ impl PageCache {
                     },
                     lsn: u64::MAX,
                 };
+                let now = Instant::now();
+                let mut reconstructed = 0u64;
+                let mut truncated = 0u64;
                 loop {
                     maxbuf.clear();
                     maxkey.pack(&mut maxbuf);
@@ -431,6 +433,7 @@ impl PageCache {
                             trace!("Reconstruct most recent page {:?}", key);
                             // force reconstruction of most recent page version
                             self.reconstruct_page(key, content)?;
+                            reconstructed += 1;
                         }
 
                         maxbuf.clear();
@@ -452,6 +455,7 @@ impl PageCache {
                                     let key = CacheKey::unpack(&mut minbuf);
                                     trace!("Reconstruct horizon page {:?}", key);
                                     self.reconstruct_page(key, content)?;
+                                    truncated += 1;
                                 }
                             }
                         }
@@ -466,6 +470,7 @@ impl PageCache {
                         break;
                     }
                 }
+                info!("Garbage collection completed in {:?}: {} pages reconstructed, {} version histories truncated", now.elapsed(), reconstructed, truncated);
             }
         }
     }