Support performance trace (#32973)

1. Add a OpenTelemetry-like shim-layer to collect traces
2. Add a simple builtin trace collector and exporter, end users could
download the diagnosis report to get the traces.

This PR's design is quite lightweight, no hard-dependency, and it is
easy to improve or remove. We can try it on gitea.com first to see
whether it works well, and fine tune the details.

---------

Co-authored-by: silverwind <me@silverwind.io>

routers/common/middleware.go

@@ -9,6 +9,7 @@ import (
 	"strings"
 
 	"code.gitea.io/gitea/modules/cache"
+	"code.gitea.io/gitea/modules/gtprof"
 	"code.gitea.io/gitea/modules/httplib"
 	"code.gitea.io/gitea/modules/reqctx"
 	"code.gitea.io/gitea/modules/setting"
@@ -52,6 +53,14 @@ func RequestContextHandler() func(h http.Handler) http.Handler {
 			ctx, finished := reqctx.NewRequestContext(req.Context(), profDesc)
 			defer finished()
 
+			ctx, span := gtprof.GetTracer().Start(ctx, gtprof.TraceSpanHTTP)
+			req = req.WithContext(ctx)
+			defer func() {
+				chiCtx := chi.RouteContext(req.Context())
+				span.SetAttributeString(gtprof.TraceAttrHTTPRoute, chiCtx.RoutePattern())
+				span.End()
+			}()
+
 			defer func() {
 				if err := recover(); err != nil {
 					RenderPanicErrorPage(respWriter, req, err) // it should never panic
@@ -75,11 +84,11 @@ func ChiRoutePathHandler() func(h http.Handler) http.Handler {
 	// make sure chi uses EscapedPath(RawPath) as RoutePath, then "%2f" could be handled correctly
 	return func(next http.Handler) http.Handler {
 		return http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
-			ctx := chi.RouteContext(req.Context())
+			chiCtx := chi.RouteContext(req.Context())
 			if req.URL.RawPath == "" {
-				ctx.RoutePath = req.URL.EscapedPath()
+				chiCtx.RoutePath = req.URL.EscapedPath()
 			} else {
-				ctx.RoutePath = req.URL.RawPath
+				chiCtx.RoutePath = req.URL.RawPath
 			}
 			next.ServeHTTP(resp, req)
 		})

routers/web/admin/admin.go

@@ -37,6 +37,7 @@ const (
 	tplSelfCheck    templates.TplName = "admin/self_check"
 	tplCron         templates.TplName = "admin/cron"
 	tplQueue        templates.TplName = "admin/queue"
+	tplPerfTrace    templates.TplName = "admin/perftrace"
 	tplStacktrace   templates.TplName = "admin/stacktrace"
 	tplQueueManage  templates.TplName = "admin/queue_manage"
 	tplStats        templates.TplName = "admin/stats"

routers/web/admin/diagnosis.go

@@ -10,13 +10,15 @@ import (
 	"time"
 
 	"code.gitea.io/gitea/modules/httplib"
+	"code.gitea.io/gitea/modules/tailmsg"
+	"code.gitea.io/gitea/modules/util"
 	"code.gitea.io/gitea/services/context"
 )
 
 func MonitorDiagnosis(ctx *context.Context) {
 	seconds := ctx.FormInt64("seconds")
-	if seconds <= 5 {
-		seconds = 5
+	if seconds <= 1 {
+		seconds = 1
 	}
 	if seconds > 300 {
 		seconds = 300
@@ -65,4 +67,16 @@ func MonitorDiagnosis(ctx *context.Context) {
 		return
 	}
 	_ = pprof.Lookup("heap").WriteTo(f, 0)
+
+	f, err = zipWriter.CreateHeader(&zip.FileHeader{Name: "perftrace.txt", Method: zip.Deflate, Modified: time.Now()})
+	if err != nil {
+		ctx.ServerError("Failed to create zip file", err)
+		return
+	}
+	for _, record := range tailmsg.GetManager().GetTraceRecorder().GetRecords() {
+		_, _ = f.Write(util.UnsafeStringToBytes(record.Time.Format(time.RFC3339)))
+		_, _ = f.Write([]byte(" "))
+		_, _ = f.Write(util.UnsafeStringToBytes((record.Content)))
+		_, _ = f.Write([]byte("\n\n"))
+	}
 }

routers/web/admin/perftrace.go

@@ -0,0 +1,18 @@
+// Copyright 2025 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package admin
+
+import (
+	"net/http"
+
+	"code.gitea.io/gitea/modules/tailmsg"
+	"code.gitea.io/gitea/services/context"
+)
+
+func PerfTrace(ctx *context.Context) {
+	monitorTraceCommon(ctx)
+	ctx.Data["PageIsAdminMonitorPerfTrace"] = true
+	ctx.Data["PerfTraceRecords"] = tailmsg.GetManager().GetTraceRecorder().GetRecords()
+	ctx.HTML(http.StatusOK, tplPerfTrace)
+}

routers/web/admin/stacktrace.go

@@ -12,10 +12,17 @@ import (
 	"code.gitea.io/gitea/services/context"
 )
 
+func monitorTraceCommon(ctx *context.Context) {
+	ctx.Data["Title"] = ctx.Tr("admin.monitor")
+	ctx.Data["PageIsAdminMonitorTrace"] = true
+	// Hide the performance trace tab in production, because it shows a lot of SQLs and is not that useful for end users.
+	// To avoid confusing end users, do not let them know this tab. End users should "download diagnosis report" instead.
+	ctx.Data["ShowAdminPerformanceTraceTab"] = !setting.IsProd
+}
+
 // Stacktrace show admin monitor goroutines page
 func Stacktrace(ctx *context.Context) {
-	ctx.Data["Title"] = ctx.Tr("admin.monitor")
-	ctx.Data["PageIsAdminMonitorStacktrace"] = true
+	monitorTraceCommon(ctx)
 
 	ctx.Data["GoroutineCount"] = runtime.NumGoroutine()
 

routers/web/web.go

@@ -720,6 +720,7 @@ func registerRoutes(m *web.Router) {
 		m.Group("/monitor", func() {
 			m.Get("/stats", admin.MonitorStats)
 			m.Get("/cron", admin.CronTasks)
+			m.Get("/perftrace", admin.PerfTrace)
 			m.Get("/stacktrace", admin.Stacktrace)
 			m.Post("/stacktrace/cancel/{pid}", admin.StacktraceCancel)
 			m.Get("/queue", admin.Queues)