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/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()