ChromeDP and high CPU usage (Golang)

I use chromedp with Go to transform html pages into images (using screenshot method) but it uses a lot of CPU. Is it ok and can i optimize it? Here how i use it (i tried to open first tab, but everything works the same, after .Run method, endpoint is not responding (app runs normally, parallel healthcheck request are OK)

Here code:

func (cdp *ChromeDP) ConvertToImage(html string) ([]byte, error) {
    var res []byte
    // You should use same context from ChromeDP struct, to avoid zombie chrome process
    ctx1, cancel1 := chromedp.NewContext(cdp.ctx)
    defer cancel1()

    var wg sync.WaitGroup
    wg.Add(1)
    if err := chromedp.Run(ctx1,
        chromedp.Navigate("about:blank"),
        chromedp.ActionFunc(func(ctx context.Context) error {
            lctx, cancel := context.WithCancel(ctx)
            chromedp.ListenTarget(lctx, func(ev interface{}) {
                if _, ok := ev.(*page.EventLoadEventFired); ok {
                    wg.Done()
                    cancel()
                }
            })

            return nil
        }),
        chromedp.ActionFunc(func(ctx context.Context) error {
            frameTree, err := page.GetFrameTree().Do(ctx)
            if err != nil {
                return err
            }

            return page.SetDocumentContent(frameTree.Frame.ID, html).Do(ctx)
        }),
        chromedp.ActionFunc(func(ctx context.Context) error {
            wg.Wait()

            return nil
        }),
        chromedp.ActionFunc(func(ctx context.Context) error {
            result, err := page.CaptureScreenshot().Do(ctx)
            if err != nil {
                return err
            }

            res = result
            return nil
        }),
    ); err != nil {
        return nil, err
    }

    return res, nil
}

(Its not wg problem, tested :D)

Solution

I was having the same problems using an alpine Docker image with a chromium installed. chromedp handles any chrome instance to execute commands.

I changed the Dockerfile to use chromedp/headless-shell:

# Build
FROM golang:latest AS build

RUN mkdir /go/src/app
COPY . /go/src/app

WORKDIR /go/src/app

RUN go mod tidy
RUN go build -o /go/src/app/main main.go

# Run
FROM chromedp/headless-shell:latest

COPY --from=build /go/src/app/main /go/src/app/
COPY --from=build /go/src/app/templates /go/src/app/templates

WORKDIR /go/src/app

EXPOSE 8080

RUN apt-get update; apt install dumb-init -y

ENTRYPOINT ["dumb-init", "--"]
CMD ["/go/src/app/main"]

I replaced an Alpine image for a Debian image (golang:latest in build stage) because chromedp/headless-shell (2nd stage in image) is based on it.

In the cluster, the service required 400% of CPU. After the change it dropped down to 2%. You can use any AWS node with it.

Another approach is to always have a running browser instance: the first chromedp.NewContext(cdp.ctx) should open an about:blank tab to never close the browser when other tabs are closed.