Initial commit: Go 1.23 release state

test/finprofiled.go

@@ -0,0 +1,79 @@
+// run
+
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Test that tiny allocations with finalizers are correctly profiled.
+// Previously profile special records could have been processed prematurely
+// (while the object is still live).
+
+package main
+
+import (
+	"runtime"
+	"time"
+	"unsafe"
+)
+
+func main() {
+	runtime.MemProfileRate = 1
+	// Allocate 1M 4-byte objects and set a finalizer for every third object.
+	// Assuming that tiny block size is 16, some objects get finalizers setup
+	// only for middle bytes. The finalizer resurrects that object.
+	// As the result, all allocated memory must stay alive.
+	const (
+		N             = 1 << 20
+		tinyBlockSize = 16 // runtime._TinySize
+	)
+	hold := make([]*int32, 0, N)
+	for i := 0; i < N; i++ {
+		x := new(int32)
+		if i%3 == 0 {
+			runtime.SetFinalizer(x, func(p *int32) {
+				hold = append(hold, p)
+			})
+		}
+	}
+	// Finalize as much as possible.
+	// Note: the sleep only increases probability of bug detection,
+	// it cannot lead to false failure.
+	for i := 0; i < 5; i++ {
+		runtime.GC()
+		time.Sleep(10 * time.Millisecond)
+	}
+	// Read memory profile.
+	var prof []runtime.MemProfileRecord
+	for {
+		if n, ok := runtime.MemProfile(prof, false); ok {
+			prof = prof[:n]
+			break
+		} else {
+			prof = make([]runtime.MemProfileRecord, n+10)
+		}
+	}
+	// See how much memory in tiny objects is profiled.
+	var totalBytes int64
+	for _, p := range prof {
+		bytes := p.AllocBytes - p.FreeBytes
+		nobj := p.AllocObjects - p.FreeObjects
+		if nobj == 0 {
+			// There may be a record that has had all of its objects
+			// freed. That's fine. Avoid a divide-by-zero and skip.
+			continue
+		}
+		size := bytes / nobj
+		if size == tinyBlockSize {
+			totalBytes += bytes
+		}
+	}
+	// 2*tinyBlockSize slack is for any boundary effects.
+	if want := N*int64(unsafe.Sizeof(int32(0))) - 2*tinyBlockSize; totalBytes < want {
+		println("got", totalBytes, "want >=", want)
+		panic("some of the tiny objects are not profiled")
+	}
+	// Just to keep hold alive.
+	if len(hold) != 0 && hold[0] == nil {
+		panic("bad")
+	}
+}