perf(history): pool zlib writers for idle page compression

Each BestSpeed writer allocates ~600 KiB of deflate state. Reuse them
across pages instead of allocating one per compressed page.

BenchmarkColdHistoryRetained10Kx120/plain-ascii: 66.3 -> 37.0 MB/op

commit: 92e0c365a3fe589fac04fa54cfc4d0d64a0b33fb
author: brice · 15d ago · 2026-10-07 16:24 UTC
parent: adadad1
signature: GPG VerifiedCD88F9E564E0102646FB6077A1A07C7C7C3E349D · arch-gpg Verified for the committer email

2 files · +19 -5

M history_storage.go +16 -5


@@ -113,6 +113,16 @@ func (c *HistoryChunk) Restore() error {
113	113		return err
114	114		}
115	115
	116	+	// pageCompressorPool reuses BestSpeed writers; each one owns ~600 KiB of
	117	+	// deflate state that would otherwise be allocated per compressed page.
	118	+	var pageCompressorPool = sync.Pool{New: func() any {
	119	+	w, err := zlib.NewWriterLevel(io.Discard, zlib.BestSpeed)
	120	+	if err != nil {
	121	+	panic(err) // BestSpeed is a valid level
	122	+	}
	123	+	return w
	124	+	}}
	125	+
116	126		func (p *sealedPage) compressIfIdle() (bool, error) {
117	127		p.mu.Lock()
118	128		defer p.mu.Unlock()

@@ -143,12 +153,13 @@ func (p *sealedPage) compressIfIdle() (bool, error) {
143	153		return false, errors.New("history page exceeds encoded backing limit")
144	154		}
145	155		var out bytes.Buffer
146		-	w, err := zlib.NewWriterLevel(&out, zlib.BestSpeed)
147		-	if err != nil {
148		-	return false, err
149		-	}
	156	+	w := pageCompressorPool.Get().(*zlib.Writer)
	157	+	w.Reset(&out)
	158	+	defer func() {
	159	+	w.Reset(io.Discard)
	160	+	pageCompressorPool.Put(w)
	161	+	}()
150	162		if _, err := w.Write(raw); err != nil {
151		-	_ = w.Close()
152	163		return false, err
153	164		}
154	165		if err := w.Close(); err != nil {

 	return err
 }
+// pageCompressorPool reuses BestSpeed writers; each one owns ~600 KiB of
+// deflate state that would otherwise be allocated per compressed page.
+var pageCompressorPool = sync.Pool{New: func() any {
+	w, err := zlib.NewWriterLevel(io.Discard, zlib.BestSpeed)
+	if err != nil {
+		panic(err) // BestSpeed is a valid level
+	}
+	return w
+}}
 func (p *sealedPage) compressIfIdle() (bool, error) {
 	p.mu.Lock()
 	defer p.mu.Unlock()
 		return false, errors.New("history page exceeds encoded backing limit")
 	}
 	var out bytes.Buffer
-	w, err := zlib.NewWriterLevel(&out, zlib.BestSpeed)
+	w := pageCompressorPool.Get().(*zlib.Writer)
-	if err != nil {
+	w.Reset(&out)
-		return false, err
+	defer func() {
-	}
+		w.Reset(io.Discard)
+		pageCompressorPool.Put(w)
+	}()
 	if _, err := w.Write(raw); err != nil {
-		_ = w.Close()
 		return false, err
 	}
 	if err := w.Close(); err != nil {

M storage_benchmark_test.go +3 -0


@@ -78,6 +78,9 @@ func BenchmarkColdHistoryRetained10Kx120(b *testing.B) {
78	78		}
79	79		}
80	80		benchmarkStorageHistorySink = h
	81	+	// Two cycles drain the compressor sync.Pool, so only the
	82	+	// history itself is measured.
	83	+	runtime.GC()
81	84		runtime.GC()
82	85		runtime.ReadMemStats(&after)
83	86		if after.HeapAlloc >= before.HeapAlloc {


@@ -78,6 +78,9 @@ func BenchmarkColdHistoryRetained10Kx120(b *testing.B) {
78	}	78		}
79	}	79		}
80	benchmarkStorageHistorySink = h	80		benchmarkStorageHistorySink = h
		81	+	// Two cycles drain the compressor sync.Pool, so only the
		82	+	// history itself is measured.
		83	+	runtime.GC()
81	runtime.GC()	84		runtime.GC()
82	runtime.ReadMemStats(&after)	85		runtime.ReadMemStats(&after)
83	if after.HeapAlloc >= before.HeapAlloc {	86		if after.HeapAlloc >= before.HeapAlloc {