feat: add pprof endpoint option for profiling by hengyoush · Pull Request #331 · hengyoush/kyanos

hengyoush · 2026-03-05T13:55:32Z

Add --pprof and --pprof-addr flags to enable pprof HTTP endpoint for runtime profiling and debugging.

Changes:

Add EnablePprof and PprofAddr to AgentOptions
Add --pprof flag to enable pprof server (default: false)
Add --pprof-addr flag to configure listen address (default: localhost:6060)
Implement startPprofServer() in agent.go

Usage:
kyanos watch --pprof kyanos watch --pprof --pprof-addr=:9090

The pprof endpoint provides access to:

/debug/pprof/heap - memory profiling
/debug/pprof/profile - CPU profiling
/debug/pprof/goroutine - goroutine dumps

vercel · 2026-03-05T13:55:38Z

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Issues-translate-bot · 2026-03-05T13:55:57Z

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Copilot

Pull request overview

Adds an opt-in pprof HTTP endpoint to the agent to support runtime profiling/debugging via new CLI flags.

Changes:

Add EnablePprof / PprofAddr to AgentOptions plus a defaulting helper (GetPprofAddr()).
Add --pprof and --pprof-addr persistent CLI flags.
Start a pprof HTTP server during agent setup when enabled.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
cmd/root.go	Wires new `--pprof` / `--pprof-addr` flags into the CLI to control profiling endpoint exposure.
agent/common/options.go	Extends `AgentOptions` with pprof settings and a helper for default address resolution.
agent/agent.go	Starts the pprof server during agent initialization when the option is enabled.

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cmd/root.go

Copilot · 2026-03-05T14:02:15Z

agent/agent.go

+		addr := opts.GetPprofAddr()
+		common.AgentLog.Infof("Starting pprof server on http://%s/debug/pprof/", addr)
+		common.AgentLog.Info("pprof endpoints: /debug/pprof/heap, /debug/pprof/profile, /debug/pprof/goroutine")
+		if err := http.ListenAndServe(addr, nil); err != nil {


startPprofServer uses http.ListenAndServe with the default server (no timeouts) and no shutdown path. Please consider using an http.Server with at least ReadHeaderTimeout/IdleTimeout and tie shutdown to options.Ctx to avoid leaving an unbounded listener running and to reduce exposure to slowloris-style resource exhaustion if users bind to non-loopback addresses.

Suggested change

if err := http.ListenAndServe(addr, nil); err != nil {

srv := &http.Server{

Addr: addr,

Handler: nil,

ReadHeaderTimeout: 5 * time.Second,

IdleTimeout: 60 * time.Second,

}

// Tie server shutdown to the agent's context, if provided.

if opts.Ctx != nil {

go func() {

<-opts.Ctx.Done()

shutdownCtx, cancel := context.WithTimeout(context.Background(), 5*time.Second)

defer cancel()

if err := srv.Shutdown(shutdownCtx); err != nil && !errors.Is(err, http.ErrServerClosed) {

common.AgentLog.Errorf("Error shutting down pprof server: %v", err)

}

}()

}

if err := srv.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {

agent/agent.go

cloudflare-workers-and-pages · 2026-03-05T14:15:31Z

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Branch Preview URL:	https://feat-pprof-endpoint.kyanos.pages.dev

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Issues-translate-bot · 2026-03-05T14:15:49Z

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Add --pprof and --pprof-addr flags to enable pprof HTTP endpoint for runtime profiling and debugging. Security improvements: - Use http.Server with ReadHeaderTimeout (10s) and IdleTimeout (120s) - Graceful shutdown tied to options.Ctx with 5s timeout - Explicit pprof handler registration instead of default serve mux Changes: - Add EnablePprof and PprofAddr to AgentOptions - Add --pprof flag to enable pprof server (default: false) - Add --pprof-addr flag to configure listen address (default: localhost:6060) - Implement startPprofServer() with proper timeouts and shutdown handling - Update docs/debug-tips.md and docs/cn/debug-tips.md with usage examples Usage: kyanos watch --pprof kyanos watch --pprof --pprof-addr=:9090 The pprof endpoint provides access to: - /debug/pprof/heap - memory profiling - /debug/pprof/profile - CPU profiling - /debug/pprof/goroutine - goroutine dumps

Copilot

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 6 comments.

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Copilot · 2026-03-05T15:29:00Z

agent/common/options.go

+func (o AgentOptions) GetPprofAddr() string {
+	if o.PprofAddr == "" {
+		return "localhost:6060"
+	}
+	return o.PprofAddr
+}


GetPprofAddr() falls back to "localhost:6060", while the CLI flag default is 127.0.0.1:6060 and docs mention localhost:6060. Using localhost can also resolve to IPv6-only on some systems. Consider using a single constant/default (preferably 127.0.0.1:6060) across flags, docs, and this fallback to avoid surprising bind behavior.

Copilot · 2026-03-05T15:29:00Z

docs/debug-tips.md

+| Endpoint | Description |
+|----------|-------------|
+| `/debug/pprof/` | Index page with all available profiles |
+| `/debug/pprof/heap` | Memory heap profile |
+| `/debug/pprof/profile` | CPU profile (30 seconds by default) |
+| `/debug/pprof/goroutine` | Goroutine dump |


The markdown table is malformed (each row starts with || instead of |), which won’t render correctly on GitHub. Remove the extra leading | so the table uses standard | ... | syntax.

Copilot · 2026-03-05T15:29:01Z

docs/cn/debug-tips.md

+| 端点 | 说明 |
+|------|------|
+| `/debug/pprof/` | 索引页面，显示所有可用的 profile |
+| `/debug/pprof/heap` | 内存堆 profile |
+| `/debug/pprof/profile` | CPU profile（默认 30 秒） |
+| `/debug/pprof/goroutine` | Goroutine 堆栈信息 |
+| `/debug/pprof/allocs` | 内存分配 profile |
+| `/debug/pprof/block` | 阻塞 profile |
+| `/debug/pprof/mutex` | 锁竞争 profile |


该 markdown 表格格式不正确（每行以 || 开头而不是 |），在 GitHub 上可能无法正常渲染。建议去掉多余的前导 |，使用标准的 | ... | 表格语法。

Copilot · 2026-03-05T15:29:01Z

agent/agent.go

 func SetupAgent(options ac.AgentOptions) {
 	startGopsServer(options)
+	startPprofServer(options)



startPprofServer(options) is called before options.Ctx is initialized (it’s set later via signal.NotifyContext). When --pprof is enabled, startPprofServer will block on <-opts.Ctx.Done() and will panic if Ctx is nil. Move the pprof startup to after options = ValidateAndRepairOptions(options) and after options.Ctx is set, or make startPprofServer tolerate a nil context (e.g., skip shutdown hook / use Background).

Copilot · 2026-03-05T15:29:01Z

docs/debug-tips.md

+By default, the pprof server listens on `localhost:6060`. You can customize the address using the `--pprof-addr` flag:
+
+```bash
+./kyanos watch --pprof --pprof-addr="0.0.0.0:9090"


This example runs the pprof HTTP server with --pprof-addr="0.0.0.0:9090", which binds the profiling endpoint to all network interfaces with no authentication or TLS. In combination with the current --pprof implementation, any host that can reach this port can download heap/CPU profiles and goroutine dumps, which commonly contain sensitive in‑memory data. Consider keeping the example bound to localhost and explicitly warning that non-loopback addresses should only be used behind strong network controls (e.g. SSH tunnel or firewall) because they expose profiling data to the network.

Copilot · 2026-03-05T15:29:02Z

docs/cn/debug-tips.md

+默认情况下，pprof 服务器监听 `localhost:6060`。你可以使用 `--pprof-addr` 标志自定义监听地址：
+
+```bash
+./kyanos watch --pprof --pprof-addr="0.0.0.0:9090"


此示例使用 --pprof-addr="0.0.0.0:9090" 启动 pprof HTTP 服务器，会在没有任何认证或 TLS 的情况下监听所有网卡。结合当前 --pprof 实现，只要能访问该端口的主机就可以获取 heap/CPU profile 和 goroutine dump，这些数据中往往包含敏感内存信息。建议文档示例保持绑定在本机地址，并明确提示只有在有严格网络控制（如 SSH 隧道或防火墙）时才应使用非回环地址，否则会把 profiling 数据暴露到网络。

dosubot bot added the size:S This PR changes 10-29 lines, ignoring generated files. label Mar 5, 2026

hengyoush requested a review from Copilot March 5, 2026 13:55

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hengyoush force-pushed the feat/pprof-endpoint branch from 4f664cc to a90b53e Compare March 5, 2026 14:15

dosubot bot added size:L This PR changes 100-499 lines, ignoring generated files. and removed size:S This PR changes 10-29 lines, ignoring generated files. labels Mar 5, 2026

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-		if err := http.ListenAndServe(addr, nil); err != nil {
+		srv := &http.Server{
+			Addr:              addr,
+			Handler:           nil,
+			ReadHeaderTimeout: 5 * time.Second,
+			IdleTimeout:       60 * time.Second,
+		}
+		// Tie server shutdown to the agent's context, if provided.
+		if opts.Ctx != nil {
+			go func() {
+				<-opts.Ctx.Done()
+				shutdownCtx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+				defer cancel()
+				if err := srv.Shutdown(shutdownCtx); err != nil && !errors.Is(err, http.ErrServerClosed) {
+					common.AgentLog.Errorf("Error shutting down pprof server: %v", err)
+				}
+			}()
+		}
+		if err := srv.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {

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