Trace upload: only send traces for current session

packages/next/src/build/index.ts

@@ -3865,6 +3865,7 @@ export default async function build(
         mode: 'build',
         projectDir: dir,
         distDir: loadedConfig.distDir,
+        isTurboSession: turboNextBuild,
         sync: true,
       })
     }

packages/next/src/cli/next-dev.ts

@@ -37,6 +37,7 @@ import os from 'os'
 import { once } from 'node:events'
 import { clearTimeout } from 'timers'
 import { flushAllTraces, trace } from '../trace'
+import { traceId } from '../trace/shared'
 
 export type NextDevOptions = {
   turbo?: boolean
@@ -137,6 +138,7 @@ const handleSessionStop = async (signal: NodeJS.Signals | number | null) => {
       mode: 'dev',
       projectDir: dir,
       distDir: config.distDir,
+      isTurboSession,
     })
   }
 
@@ -277,6 +279,7 @@ const nextDev = async (
           ...defaultEnv,
           TURBOPACK: process.env.TURBOPACK,
           NEXT_PRIVATE_WORKER: '1',
+          NEXT_PRIVATE_TRACE_ID: traceId,
           NODE_EXTRA_CA_CERTS: startServerOptions.selfSignedCertificate
             ? startServerOptions.selfSignedCertificate.rootCA
             : defaultEnv.NODE_EXTRA_CA_CERTS,
@@ -309,6 +312,7 @@ const nextDev = async (
               mode: 'dev',
               projectDir: dir,
               distDir: config.distDir,
+              isTurboSession,
               sync: true,
             })
           }

packages/next/src/trace/report/to-json.ts

@@ -1,5 +1,4 @@
-import { randomBytes } from 'crypto'
-import { traceGlobals } from '../shared'
+import { traceGlobals, traceId } from '../shared'
 import fs from 'fs'
 import path from 'path'
 import { PHASE_DEVELOPMENT_SERVER } from '../../shared/lib/constants'
@@ -44,7 +43,6 @@ export function batcher(reportEvents: (evts: Event[]) => Promise<void>) {
 }
 
 let writeStream: RotatingWriteStream
-let traceId: string
 let batch: ReturnType<typeof batcher> | undefined
 
 const writeStreamOptions = {
@@ -117,10 +115,6 @@ const reportToLocalHost = (event: TraceEvent) => {
     return
   }
 
-  if (!traceId) {
-    traceId = process.env.TRACE_ID || randomBytes(8).toString('hex')
-  }
-
   if (!batch) {
     batch = batcher(async (events: Event[]) => {
       if (!writeStream) {

packages/next/src/trace/shared.ts

@@ -1,3 +1,5 @@
+import { randomBytes } from 'node:crypto'
+
 let _traceGlobals: Map<any, any> = (global as any)._traceGlobals
 
 if (!_traceGlobals) {
@@ -9,3 +11,8 @@ export const traceGlobals: Map<any, any> = _traceGlobals
 export const setGlobal = (key: any, val: any) => {
   traceGlobals.set(key, val)
 }
+
+export const traceId =
+  process.env.TRACE_ID ||
+  process.env.NEXT_PRIVATE_TRACE_ID ||
+  randomBytes(8).toString('hex')

packages/next/src/trace/trace-uploader.ts

@@ -7,7 +7,6 @@ import os from 'os'
 import { createInterface } from 'readline'
 import { createReadStream } from 'fs'
 import path from 'path'
-import { Telemetry } from '../telemetry/storage'
 
 const COMMON_ALLOWED_EVENTS = ['memory-usage']
 
@@ -66,7 +65,19 @@ const {
 const isDebugEnabled = !!NEXT_TRACE_UPLOAD_DEBUG || !!NEXT_TRACE_UPLOAD_FULL
 const shouldUploadFullTrace = !!NEXT_TRACE_UPLOAD_FULL
 
-const [, , traceUploadUrl, mode, projectDir, distDir] = process.argv
+const [
+  ,
+  ,
+  traceUploadUrl,
+  mode,
+  projectDir,
+  distDir,
+  _isTurboSession,
+  traceId,
+  anonymousId,
+  sessionId,
+] = process.argv
+const isTurboSession = _isTurboSession === 'true'
 
 type TraceRequestBody = {
   metadata: TraceMetadata
@@ -105,8 +116,6 @@ interface TraceMetadata {
     )
   ).version
 
-  const telemetry = new Telemetry({ distDir })
-
   const projectPkgJsonPath = await findUp('package.json')
   assert(projectPkgJsonPath)
 
@@ -129,11 +138,15 @@ interface TraceMetadata {
     crlfDelay: Infinity,
   })
 
-  let isTurboSession = false
-  const traces = new Map<string, TraceEvent[]>()
+  const sessionTrace = []
   for await (const line of readLineInterface) {
     const lineEvents: TraceEvent[] = JSON.parse(line)
     for (const event of lineEvents) {
+      if (event.traceId !== traceId) {
+        // Only consider events for the current session
+        continue
+      }
+
       if (
         // Always include root spans
         event.parentId === undefined ||
@@ -142,22 +155,14 @@ interface TraceMetadata {
           ? DEV_ALLOWED_EVENTS.has(event.name)
           : BUILD_ALLOWED_EVENTS.has(event.name))
       ) {
-        let trace = traces.get(event.traceId)
-        if (trace === undefined) {
-          trace = []
-          traces.set(event.traceId, trace)
-        }
-        if (typeof event.tags.isTurbopack === 'boolean') {
-          isTurboSession = event.tags.isTurbopack
-        }
-        trace.push(event)
+        sessionTrace.push(event)
       }
     }
   }
 
   const body: TraceRequestBody = {
     metadata: {
-      anonymousId: telemetry.anonymousId,
+      anonymousId,
       arch: os.arch(),
       commit,
       cpus: os.cpus().length,
@@ -166,9 +171,12 @@ interface TraceMetadata {
       nextVersion,
       pkgName,
       platform: os.platform(),
-      sessionId: telemetry.sessionId,
+      sessionId,
     },
-    traces: [...traces.values()],
+    // The trace file can contain events spanning multiple sessions.
+    // Only submit traces for the current session, as the metadata we send is
+    // intended for this session only.
+    traces: [sessionTrace],
   }
 
   if (isDebugEnabled) {

packages/next/src/trace/trace.ts

@@ -52,10 +52,6 @@ export class Span {
     this.name = name
     this.parentId = parentId ?? defaultParentSpanId
     this.attrs = attrs ? { ...attrs } : {}
-    if (this.parentId === undefined) {
-      // Attach additional information to root spans
-      this.attrs.isTurbopack = Boolean(process.env.TURBOPACK)
-    }
 
     this.status = SpanStatus.Started
     this.id = getId()

packages/next/src/trace/upload-trace.ts

@@ -1,17 +1,23 @@
+import { traceId } from './shared'
+import { Telemetry } from '../telemetry/storage'
+
 export default function uploadTrace({
   traceUploadUrl,
   mode,
   projectDir,
   distDir,
+  isTurboSession,
   sync,
 }: {
   traceUploadUrl: string
   mode: 'dev' | 'build'
   projectDir: string
   distDir: string
+  isTurboSession: boolean
   sync?: boolean
 }) {
   const { NEXT_TRACE_UPLOAD_DEBUG } = process.env
+  const telemetry = new Telemetry({ distDir })
 
   // Note: cross-spawn is not used here as it causes
   // a new command window to appear when we don't want it to
@@ -33,6 +39,10 @@ export default function uploadTrace({
       mode,
       projectDir,
       distDir,
+      String(isTurboSession),
+      traceId,
+      telemetry.anonymousId,
+      telemetry.sessionId,
     ],
     {
       detached: !NEXT_TRACE_UPLOAD_DEBUG,