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WrapHandleFunc: Data race when running HTTP server in a goroutine #957

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bentcoder opened this issue Aug 31, 2024 · 8 comments
Open

WrapHandleFunc: Data race when running HTTP server in a goroutine #957

bentcoder opened this issue Aug 31, 2024 · 8 comments
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@bentcoder
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bentcoder commented Aug 31, 2024 •
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Hi,

When starting the HTTP server in a goroutine (ListenAndServe()), NewRelic causes data race. If you take it out, it is fine. What is the problem here and a solution please?

Thanks

go version go1.23.0 darwin/amd64

package main

import (
    "context"
    "log"
    "log/slog"
    "net/http"
    "os"
    "os/signal"
    "syscall"
    "time"

    "github.com/newrelic/go-agent/v3/newrelic"
)

const (
    licence = "1234567890qwerty"
)

func main() {
    // NewRelic ----------------------------------------------------------------
    app, err := newrelic.NewApplication(
        newrelic.ConfigAppName("Rest"),
        newrelic.ConfigLicense(licence),
        newrelic.ConfigAppLogForwardingEnabled(true),
    )
    if err != nil {
        log.Fatalln(err)
    }

    // HTTP api ----------------------------------------------------------------
    userCreatePath, userCreateHandle := newrelic.WrapHandleFunc(app, "POST /api/v1/users", func(w http.ResponseWriter, r *http.Request) {
        slog.Info("User created")
    })

    // HTTP router -------------------------------------------------------------
    rtr := http.NewServeMux()
    rtr.HandleFunc(userCreatePath, userCreateHandle)

    // HTTP server -------------------------------------------------------------
    srv := &http.Server{Handler: rtr, Addr: ":1234"}

    go func() {
        slog.Debug("Server started")
        if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
            slog.Error("Server start", "error", err)
        }
    }()

    ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
    defer stop()

    <-ctx.Done()

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

    if err := srv.Shutdown(ctx); err != nil {
        slog.Error("Server shutdown", "error", err)
    } else {
        slog.Debug("Server shutdown")
    }
}
$ go run -race cmd/api/main.go 
==================
WARNING: DATA RACE
Read at 0x00c00028c518 by goroutine 47:
  github.com/newrelic/go-agent/v3/newrelic.WrapHandle.func1()
      /Users/myself/go/pkg/mod/github.com/newrelic/go-agent/[email protected]/newrelic/instrumentation.go:55 +0x10c
  net/http.HandlerFunc.ServeHTTP()
      /usr/local/Cellar/go/1.23.0/libexec/src/net/http/server.go:2220 +0x47
  github.com/newrelic/go-agent/v3/newrelic.WrapHandleFunc.func1()
      /Users/myself/go/pkg/mod/github.com/newrelic/go-agent/[email protected]/newrelic/instrumentation.go:152 +0x5a
  net/http.HandlerFunc.ServeHTTP()
      /usr/local/Cellar/go/1.23.0/libexec/src/net/http/server.go:2220 +0x47
  net/http.(*ServeMux).ServeHTTP()
      /usr/local/Cellar/go/1.23.0/libexec/src/net/http/server.go:2747 +0x255
  net/http.serverHandler.ServeHTTP()
      /usr/local/Cellar/go/1.23.0/libexec/src/net/http/server.go:3210 +0x2a1
  net/http.(*conn).serve()
      /usr/local/Cellar/go/1.23.0/libexec/src/net/http/server.go:2092 +0x12a4
  net/http.(*Server).Serve.gowrap3()
      /usr/local/Cellar/go/1.23.0/libexec/src/net/http/server.go:3360 +0x4f

Previous write at 0x00c00028c518 by goroutine 7:
  github.com/newrelic/go-agent/v3/newrelic.(*app).setState()
      /Users/myself/go/pkg/mod/github.com/newrelic/go-agent/[email protected]/newrelic/internal_app.go:508 +0xaa
  github.com/newrelic/go-agent/v3/newrelic.(*app).process()
      /Users/myself/go/pkg/mod/github.com/newrelic/go-agent/[email protected]/newrelic/internal_app.go:322 +0x103c
  github.com/newrelic/go-agent/v3/newrelic.newApp.gowrap1()
      /Users/myself/go/pkg/mod/github.com/newrelic/go-agent/[email protected]/newrelic/internal_app.go:464 +0x33

Goroutine 47 (running) created at:
  net/http.(*Server).Serve()
      /usr/local/Cellar/go/1.23.0/libexec/src/net/http/server.go:3360 +0x8ec
  net/http.(*Server).ListenAndServe()
      /usr/local/Cellar/go/1.23.0/libexec/src/net/http/server.go:3259 +0xbc
  main.main.func3()
      /Users/myself/dev/golang/mix/rest/cmd/api/main.go:49 +0x46

Goroutine 7 (running) created at:
  github.com/newrelic/go-agent/v3/newrelic.newApp()
      /Users/myself/go/pkg/mod/github.com/newrelic/go-agent/[email protected]/newrelic/internal_app.go:464 +0xc2b
  github.com/newrelic/go-agent/v3/newrelic.NewApplication()
      /Users/myself/go/pkg/mod/github.com/newrelic/go-agent/[email protected]/newrelic/application.go:259 +0x2fb
  main.main()
      /Users/myself/dev/golang/mix/rest/cmd/api/main.go:22 +0x1aa
==================
==================
WARNING: DATA RACE
Read at 0x00c00028efd8 by goroutine 47:
  github.com/newrelic/go-agent/v3/newrelic.WrapHandle.func1()
      /Users/myself/go/pkg/mod/github.com/newrelic/go-agent/[email protected]/newrelic/instrumentation.go:55 +0x184
  net/http.HandlerFunc.ServeHTTP()
      /usr/local/Cellar/go/1.23.0/libexec/src/net/http/server.go:2220 +0x47
  github.com/newrelic/go-agent/v3/newrelic.WrapHandleFunc.func1()
      /Users/myself/go/pkg/mod/github.com/newrelic/go-agent/[email protected]/newrelic/instrumentation.go:152 +0x5a
  net/http.HandlerFunc.ServeHTTP()
      /usr/local/Cellar/go/1.23.0/libexec/src/net/http/server.go:2220 +0x47
  net/http.(*ServeMux).ServeHTTP()
      /usr/local/Cellar/go/1.23.0/libexec/src/net/http/server.go:2747 +0x255
  net/http.serverHandler.ServeHTTP()
      /usr/local/Cellar/go/1.23.0/libexec/src/net/http/server.go:3210 +0x2a1
  net/http.(*conn).serve()
      /usr/local/Cellar/go/1.23.0/libexec/src/net/http/server.go:2092 +0x12a4
  net/http.(*Server).Serve.gowrap3()
      /usr/local/Cellar/go/1.23.0/libexec/src/net/http/server.go:3360 +0x4f

Previous write at 0x00c00028efd8 by goroutine 8:
  github.com/newrelic/go-agent/v3/newrelic.newAppRun()
      /Users/myself/go/pkg/mod/github.com/newrelic/go-agent/[email protected]/newrelic/app_run.go:54 +0x2c7
  github.com/newrelic/go-agent/v3/newrelic.(*app).connectRoutine()
      /Users/myself/go/pkg/mod/github.com/newrelic/go-agent/[email protected]/newrelic/internal_app.go:145 +0x5a4
  github.com/newrelic/go-agent/v3/newrelic.newApp.gowrap2()
      /Users/myself/go/pkg/mod/github.com/newrelic/go-agent/[email protected]/newrelic/internal_app.go:465 +0x33

Goroutine 47 (running) created at:
  net/http.(*Server).Serve()
      /usr/local/Cellar/go/1.23.0/libexec/src/net/http/server.go:3360 +0x8ec
  net/http.(*Server).ListenAndServe()
      /usr/local/Cellar/go/1.23.0/libexec/src/net/http/server.go:3259 +0xbc
  main.main.func3()
      /Users/myself/dev/golang/mix/rest/cmd/api/main.go:49 +0x46

Goroutine 8 (finished) created at:
  github.com/newrelic/go-agent/v3/newrelic.newApp()
      /Users/myself/go/pkg/mod/github.com/newrelic/go-agent/[email protected]/newrelic/internal_app.go:465 +0xcaa
  github.com/newrelic/go-agent/v3/newrelic.NewApplication()
      /Users/myself/go/pkg/mod/github.com/newrelic/go-agent/[email protected]/newrelic/application.go:259 +0x2fb
  main.main()
      /Users/myself/dev/golang/mix/rest/cmd/api/main.go:22 +0x1aa
==================
2024/08/30 22:55:15 INFO User created
@bentcoder bentcoder added the bug label Aug 31, 2024
@bentcoder bentcoder changed the title Data race when running HTTP server in a goroutine WrapHandleFunc: Data race when running HTTP server in a goroutine Aug 31, 2024
@nr-swilloughby
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is this happening inside a container or AWS runtime environment or something, or does it happen if running the code on an ordinary workstation shell?

@nr-swilloughby
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I tried running your code example but did not see the race condition show up so far. Using go version go1.23.0 darwin/arm64. Will continue trying to reproduce the error.

@bentcoder
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bentcoder commented Aug 31, 2024 •
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It happens in VSCode terminal, native OS terminal and iTerm2. I don't use Docker for this.

I hope you are using -race flag with go run command.

@nr-swilloughby
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Thanks. Yes, I'm using -race. I'll keep looking.

@bentcoder
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Just realised, it even happens when not using goroutine at all. Bottom part is like this:

	...

	// HTTP server
	srv := &http.Server{Handler: rtr, Addr: ":1234"}

	slog.Debug("Server started")
	if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
		slog.Error("Server start", "error", err)
	} else {
		slog.Debug("Server shutdown")
	}
}

@nr-swilloughby
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I'm still not able to reproduce your error on my end, which may simply be a matter of timing. However, when analyzing the code flow that you're reporting, I believe I see where a race condition might be possible so I'm addressing that to see if that resolves what you're seeing.

@nr-swilloughby
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I have merged a proposed fix to our develop branch which is where our code gets staged shortly before release. Could you try pulling a copy of the agent from that branch and try compiling with that to see if that solves your issue?

@bentcoder
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Working fine now. Thank you.

REF:

go 1.23.0

require github.com/newrelic/go-agent/v3 v3.29.1-0.20240905201932-d95445cf6c4e

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@bentcoder @nr-swilloughby