上面是一个middleware实现, 最终cpu信息会记录到profMap中. (要多次调用接口才能看到效果).

do_pprof.go

func Handler(meta endpoint.Meta, next endpoint.Endpoint) endpoint.Endpoint {
	profMapLock.Lock()
	defer profMapLock.Unlock()
	traceBytes := []byte{}
	tracePtr := &traceBytes

	var lock sync.Mutex
	var buf bytes.Buffer
	var traceBuf bytes.Buffer
	var hasMerged bool

	setEnabled()

	// Prepare buffers for this endpoint
	merged := new(profile.Profile)
	profKey := meta.Service + "." + meta.Name
	profMap[profKey] = &profileDump{
		profile: merged,
		trace:   tracePtr,
	}
	profWriter := bufio.NewWriter(&buf)
	traceWriter := bufio.NewWriter(&traceBuf)

	return func(ctx context.Context, request interface{}) (metadata metadata.Metadata, response interface{}, err error) {

		// Lock to ensure only one endpoint is profiled at a time
		lock.Lock()
		defer lock.Unlock()

		// Profile just this endpoint
		if err := pprof.StartCPUProfile(profWriter); err != nil {
			// If already enabled, don't profile
			return next(ctx, request)
		}

		if err := trace.Start(traceWriter); err != nil {
			// If already enabled, don't trace
			return next(ctx, request)
		}

		metadata, response, err = next(ctx, request)

		trace.Stop()
		_ = traceWriter.Flush()

		pprof.StopCPUProfile()
		_ = profWriter.Flush()

		*tracePtr = traceBuf.Bytes()

		// Parse and merge profiles ready for converting to flamegraph
		// This is done eagerly but could be deferred until the flamegraph is called
		thisProf, parseErr := profile.Parse(bufio.NewReader(&buf))

		buf.Reset()
		traceBuf.Reset()

		if parseErr == nil {
			if hasMerged {
				m, merr := profile.Merge([]*profile.Profile{merged, thisProf})
				if merr == nil {
					*merged = *m
				}
				return
			}
			*merged = *thisProf
			hasMerged = true
		}

		return	
	}
}