From b254dce8a1564af3eed5fea02c2511c9b40d435f Mon Sep 17 00:00:00 2001
From: "Alex Chi Z." <4198311+skyzh@users.noreply.github.com>
Date: Tue, 1 Jul 2025 10:00:27 -0700
Subject: [PATCH] feat(pageserver): report compaction progress (#12401)

## Problem

close https://github.com/neondatabase/neon/issues/11528

## Summary of changes

Gives us better observability of compaction progress.

- Image creation: num of partition processed / total partition
- Gc-compaction: index of the in the queue / total items for a full
compaction
- Shard ancestor compaction: layers to rewrite / total layers

Signed-off-by: Alex Chi Z <chi@neon.tech>
---
 pageserver/src/tenant/timeline.rs            | 18 +++++++++++---
 pageserver/src/tenant/timeline/compaction.rs | 26 ++++++++++++++------
 2 files changed, 34 insertions(+), 10 deletions(-)

diff --git a/pageserver/src/tenant/timeline.rs b/pageserver/src/tenant/timeline.rs
index 08bc6d4a59..aca44718fa 100644
--- a/pageserver/src/tenant/timeline.rs
+++ b/pageserver/src/tenant/timeline.rs
@@ -5308,6 +5308,7 @@ impl Timeline {
         ctx: &RequestContext,
         img_range: Range<Key>,
         io_concurrency: IoConcurrency,
+        progress: Option<(usize, usize)>,
     ) -> Result<ImageLayerCreationOutcome, CreateImageLayersError> {
         let mut wrote_keys = false;
 
@@ -5384,11 +5385,15 @@ impl Timeline {
             }
         }
 
+        let progress_report = progress
+            .map(|(idx, total)| format!("({idx}/{total}) "))
+            .unwrap_or_default();
         if wrote_keys {
             // Normal path: we have written some data into the new image layer for this
             // partition, so flush it to disk.
             info!(
-                "produced image layer for rel {}",
+                "{} produced image layer for rel {}",
+                progress_report,
                 ImageLayerName {
                     key_range: img_range.clone(),
                     lsn
@@ -5398,7 +5403,12 @@ impl Timeline {
                 unfinished_image_layer: image_layer_writer,
             })
         } else {
-            tracing::debug!("no data in range {}-{}", img_range.start, img_range.end);
+            tracing::debug!(
+                "{} no data in range {}-{}",
+                progress_report,
+                img_range.start,
+                img_range.end
+            );
             Ok(ImageLayerCreationOutcome::Empty)
         }
     }
@@ -5633,7 +5643,8 @@ impl Timeline {
             }
         }
 
-        for partition in partition_parts.iter() {
+        let total = partition_parts.len();
+        for (idx, partition) in partition_parts.iter().enumerate() {
             if self.cancel.is_cancelled() {
                 return Err(CreateImageLayersError::Cancelled);
             }
@@ -5718,6 +5729,7 @@ impl Timeline {
                     ctx,
                     img_range.clone(),
                     io_concurrency,
+                    Some((idx, total)),
                 )
                 .await?
             } else {
diff --git a/pageserver/src/tenant/timeline/compaction.rs b/pageserver/src/tenant/timeline/compaction.rs
index 13a4f82607..43573c28a2 100644
--- a/pageserver/src/tenant/timeline/compaction.rs
+++ b/pageserver/src/tenant/timeline/compaction.rs
@@ -101,7 +101,11 @@ pub enum GcCompactionQueueItem {
         /// Whether the compaction is triggered automatically (determines whether we need to update L2 LSN)
         auto: bool,
     },
-    SubCompactionJob(CompactOptions),
+    SubCompactionJob {
+        i: usize,
+        total: usize,
+        options: CompactOptions,
+    },
     Notify(GcCompactionJobId, Option<Lsn>),
 }
 
@@ -163,7 +167,7 @@ impl GcCompactionQueueItem {
                 running,
                 job_id: id.0,
             }),
-            GcCompactionQueueItem::SubCompactionJob(options) => Some(CompactInfoResponse {
+            GcCompactionQueueItem::SubCompactionJob { options, .. } => Some(CompactInfoResponse {
                 compact_key_range: options.compact_key_range,
                 compact_lsn_range: options.compact_lsn_range,
                 sub_compaction: options.sub_compaction,
@@ -489,7 +493,7 @@ impl GcCompactionQueue {
                 .map(|job| job.compact_lsn_range.end)
                 .max()
                 .unwrap();
-            for job in jobs {
+            for (i, job) in jobs.into_iter().enumerate() {
                 // Unfortunately we need to convert the `GcCompactJob` back to `CompactionOptions`
                 // until we do further refactors to allow directly call `compact_with_gc`.
                 let mut flags: EnumSet<CompactFlags> = EnumSet::default();
@@ -507,7 +511,11 @@ impl GcCompactionQueue {
                     compact_lsn_range: Some(job.compact_lsn_range.into()),
                     sub_compaction_max_job_size_mb: None,
                 };
-                pending_tasks.push(GcCompactionQueueItem::SubCompactionJob(options));
+                pending_tasks.push(GcCompactionQueueItem::SubCompactionJob {
+                    options,
+                    i,
+                    total: jobs_len,
+                });
             }
 
             if !auto {
@@ -651,7 +659,7 @@ impl GcCompactionQueue {
                     }
                 }
             }
-            GcCompactionQueueItem::SubCompactionJob(options) => {
+            GcCompactionQueueItem::SubCompactionJob { options, i, total } => {
                 // TODO: error handling, clear the queue if any task fails?
                 let _gc_guard = match gc_block.start().await {
                     Ok(guard) => guard,
@@ -663,6 +671,7 @@ impl GcCompactionQueue {
                         )));
                     }
                 };
+                info!("running gc-compaction subcompaction job {}/{}", i, total);
                 let res = timeline.compact_with_options(cancel, options, ctx).await;
                 let compaction_result = match res {
                     Ok(res) => res,
@@ -1591,13 +1600,15 @@ impl Timeline {
         let started = Instant::now();
 
         let mut replace_image_layers = Vec::new();
+        let total = layers_to_rewrite.len();
 
-        for layer in layers_to_rewrite {
+        for (i, layer) in layers_to_rewrite.into_iter().enumerate() {
             if self.cancel.is_cancelled() {
                 return Err(CompactionError::ShuttingDown);
             }
 
-            info!(layer=%layer, "rewriting layer after shard split");
+            info!(layer=%layer, "rewriting layer after shard split: {}/{}", i, total);
+
             let mut image_layer_writer = ImageLayerWriter::new(
                 self.conf,
                 self.timeline_id,
@@ -4343,6 +4354,7 @@ impl TimelineAdaptor {
                 ctx,
                 key_range.clone(),
                 IoConcurrency::sequential(),
+                None,
             )
             .await?;