From 4aef0237657e052c14f88562490415085fbfa820 Mon Sep 17 00:00:00 2001
From: Jordan Whited <jordan@tailscale.com>
Date: Tue, 26 May 2026 17:13:48 -0700
Subject: [PATCH] cmd/tailscaled,types/logger: remove TS_DEBUG_MEMORY and
 associated logger

Commit e5a8cf3b1 added feature/runtimemetrics, which emits heap bytes
and total process memory as clientmetrics when the
NodeAttrEmitRuntimeMetrics capability is set. That subsumes the job of
the TS_DEBUG_MEMORY envknob, whose only effect is to prefix every log
line with Go heap+stack and Maxrss via logger.RusagePrefixLog.

Updates tailscale/corp#39434

Signed-off-by: Jordan Whited <jordan@tailscale.com>
---
 cmd/tailscaled/tailscaled.go   |  3 ---
 types/logger/rusage.go         | 23 -----------------------
 types/logger/rusage_stub.go    | 11 -----------
 types/logger/rusage_syscall.go | 29 -----------------------------
 4 files changed, 66 deletions(-)
 delete mode 100644 types/logger/rusage.go
 delete mode 100644 types/logger/rusage_stub.go
 delete mode 100644 types/logger/rusage_syscall.go

diff --git a/cmd/tailscaled/tailscaled.go b/cmd/tailscaled/tailscaled.go
index 9ecf84055..42126f0c9 100644
--- a/cmd/tailscaled/tailscaled.go
+++ b/cmd/tailscaled/tailscaled.go
@@ -460,9 +460,6 @@ func run() (err error) {
 		return nil
 	}
 
-	if envknob.Bool("TS_DEBUG_MEMORY") {
-		logf = logger.RusagePrefixLog(logf)
-	}
 	logf = logger.RateLimitedFn(logf, 5*time.Second, 5, 100)
 
 	if envknob.Bool("TS_PLEASE_PANIC") {
diff --git a/types/logger/rusage.go b/types/logger/rusage.go
deleted file mode 100644
index c1bbbaa53..000000000
--- a/types/logger/rusage.go
+++ /dev/null
@@ -1,23 +0,0 @@
-// Copyright (c) Tailscale Inc & contributors
-// SPDX-License-Identifier: BSD-3-Clause
-
-package logger
-
-import (
-	"fmt"
-	"runtime"
-)
-
-// RusagePrefixLog returns a Logf func wrapping the provided logf func that adds
-// a prefixed log message to each line with the current binary memory usage
-// and max RSS.
-func RusagePrefixLog(logf Logf) Logf {
-	return func(f string, argv ...any) {
-		var m runtime.MemStats
-		runtime.ReadMemStats(&m)
-		goMem := float64(m.HeapInuse+m.StackInuse) / (1 << 20)
-		maxRSS := rusageMaxRSS()
-		pf := fmt.Sprintf("%.1fM/%.1fM %s", goMem, maxRSS, f)
-		logf(pf, argv...)
-	}
-}
diff --git a/types/logger/rusage_stub.go b/types/logger/rusage_stub.go
deleted file mode 100644
index e94478ef7..000000000
--- a/types/logger/rusage_stub.go
+++ /dev/null
@@ -1,11 +0,0 @@
-// Copyright (c) Tailscale Inc & contributors
-// SPDX-License-Identifier: BSD-3-Clause
-
-//go:build windows || wasm || plan9 || tamago
-
-package logger
-
-func rusageMaxRSS() float64 {
-	// TODO(apenwarr): Substitute Windows equivalent of Getrusage() here.
-	return 0
-}
diff --git a/types/logger/rusage_syscall.go b/types/logger/rusage_syscall.go
deleted file mode 100644
index 25b026994..000000000
--- a/types/logger/rusage_syscall.go
+++ /dev/null
@@ -1,29 +0,0 @@
-// Copyright (c) Tailscale Inc & contributors
-// SPDX-License-Identifier: BSD-3-Clause
-
-//go:build !windows && !wasm && !plan9 && !tamago
-
-package logger
-
-import (
-	"runtime"
-
-	"golang.org/x/sys/unix"
-)
-
-func rusageMaxRSS() float64 {
-	var ru unix.Rusage
-	err := unix.Getrusage(unix.RUSAGE_SELF, &ru)
-	if err != nil {
-		return 0
-	}
-
-	rss := float64(ru.Maxrss)
-	if runtime.GOOS == "darwin" || runtime.GOOS == "ios" {
-		rss /= 1 << 20 // ru_maxrss is bytes on darwin
-	} else {
-		// ru_maxrss is kilobytes elsewhere (linux, openbsd, etc)
-		rss /= 1 << 10
-	}
-	return rss
-}