🐛 template/html: Cannot Clone "layouts/main" after it has executed #818

suntong · 2020-09-20T17:36:53Z

Fiber version

v2.0.2

Issue description

Continue from #814, which were having the problem of

html/template: cannot Clone "layouts/main" after it has executed

it seems only occurs to html/template, and
the solution was to reload the template engine.

However, the reload was not necessary before, and it only works for simple demo examples. I.e., my demo is working after the fix, while my real application is still suffering from the issue.

Here are the details:

Code snippet

package main

import "github.com/gofiber/fiber/v2"

func main() {
  app := fiber.New()

  // Steps to reproduce
	app.Get("/layout", func(c *fiber.Ctx) error {
		// Render index within layouts/main
		return c.Render("index", fiber.Map{
			"Title": "Hello, World!",
		}, "layouts/main")
	})

  log.Fatal(app.Listen(":3000"))
}

I've setup a new demo at https://gitlab.com/suntong/template-html/,

everything about the html template handing is the same as my real application, and even the middlewares
the only thing I see different from the two is there are more business logic in my real application
yet my real application can render the html template only once, then it get to the same error again, while the above published demo can sustain the repeated requests.

Here are the test logs:

$ cat go.mod 
module template-html

go 1.14

require (
        github.com/gofiber/fiber/v2 v2.0.2
        github.com/gofiber/template v1.6.2
)

# Start my real application

$ curl http://localhost:5858/layout
<!DOCTYPE html>
<html lang="en" dir="ltr">

<head>
  <meta charset="utf-8" />
  <meta http-equiv="X-UA-Compatible" content="IE=edge" />
  <meta name="viewport" content="width=device-width, initial-scale=1" />
  
  <link href="https://fonts.googleapis.com/css?family=Montserrat:400,500|Poppins:400,500,600,700|Roboto:400,500"
  rel="stylesheet" />
  <link href="https://cdn.materialdesignicons.com/3.0.39/css/materialdesignicons.min.css" rel="stylesheet" />
  
  <link id="sleek-css" rel="stylesheet" href="assets/css/sleek.min.css" />

  <title>Hello, World! - </title>
</head>

<body id="body">

<h1>Hello, World!</h1>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
  <script src="assets/plugins/slimscrollbar/jquery.slimscroll.min.js"></script>
  <script src="assets/js/sleek.bundle.js"></script>
</body>

</html>

# Start my demo
$ curl http://localhost:3000/layout
<!DOCTYPE html>
<html lang="en" dir="ltr">

<head>
  <meta charset="utf-8" />
  <meta http-equiv="X-UA-Compatible" content="IE=edge" />
  <meta name="viewport" content="width=device-width, initial-scale=1" />
  
  <link href="https://fonts.googleapis.com/css?family=Montserrat:400,500|Poppins:400,500,600,700|Roboto:400,500"
  rel="stylesheet" />
  <link href="https://cdn.materialdesignicons.com/3.0.39/css/materialdesignicons.min.css" rel="stylesheet" />
  
  <link id="sleek-css" rel="stylesheet" href="assets/css/sleek.min.css" />

  <title>Hello, World! - </title>
</head>

<body id="body">

<h1>Hello, World!</h1>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
  <script src="assets/plugins/slimscrollbar/jquery.slimscroll.min.js"></script>
  <script src="assets/js/sleek.bundle.js"></script>
</body>

</html>

# repeat
$ curl http://localhost:5858/layout
html/template: cannot Clone "layouts/main" after it has executed

$ curl -s http://localhost:3000/layout | tail -6
  <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
  <script src="assets/plugins/slimscrollbar/jquery.slimscroll.min.js"></script>
  <script src="assets/js/sleek.bundle.js"></script>
</body>

</html>

. . .

$ curl -s http://localhost:3000/layout | tail -6
  <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
  <script src="assets/plugins/slimscrollbar/jquery.slimscroll.min.js"></script>
  <script src="assets/js/sleek.bundle.js"></script>
</body>

</html>

i.e., my demo can sustain the repeated requests while my real application cannot.

Again, everything about the html template handing is the same between my demo and my real application, and even the middlewares. So I'm suspecting that any other mildly complicated template/html based application would suffer from the same issue, caused by the same problem that needs to reload the template engine. If someone has to have my real application to duplicate the issue, please give me your gitlab id so that I can add you to my private project.

Thanks

The text was updated successfully, but these errors were encountered:

anton7r · 2020-09-20T17:56:57Z

i have the same issue

anton7r · 2020-09-21T11:14:05Z

im looking into it!

anton7r · 2020-09-21T12:50:13Z

from my observations the issue does not seem to be with gofiber/template/html.

i went to take a deeper dive into the html/template package

in the template.go file after i removed the check for that highlighted src.EscapeErr it started to work expectedly.

so i believe this issue should be moved to golang/go/issues

anton7r · 2020-09-21T12:57:21Z

after i further modified the template.go file and got it to print out the new error message it says:
html/template: cannot Clone "layouts/main" because of an escape error: "template escaped correctly"

anton7r · 2020-09-21T13:02:34Z

i think removing this from the golang/go/html/template/template.go and refactoring the code would fix the issue

Fenny · 2020-09-24T19:18:49Z

The question is why is an escapeErr set in the first place, maybe this is something we can solve on our end.

suntong · 2020-09-24T19:21:41Z

The question is why is an escapeErr set in the first place, maybe this is something we can solve on our end.

Yep, totally agree.

Giving the fact that V1 has no problems at all all the time and V2 suddenly has such problem, I'd highly suspect that the issue is V2 related, not the Go html/template package.

anton7r · 2020-09-25T11:18:14Z

The question is why is an escapeErr set in the first place, maybe this is something we can solve on our end.

Yep, totally agree.

Giving the fact that V1 has no problems at all all the time and V2 suddenly has such problem, I'd highly suspect that the issue is V2 related, not the Go html/template package.

Yes it seems like it is actually an issue with V2, because the the template.go file has not been drastically modified in the past 2 years.

But maybe someone should refactor that file?

Fenny · 2020-09-25T11:54:00Z

I have some time tomorrow to debug this issue, I will post updates here 👍

john-gold · 2020-09-27T18:33:14Z

Hello, so far I'm only getting this error if

*Engine.Reload == false

anton7r · 2020-09-28T17:26:59Z

i propose that we have a fork of the orginal golang/go project where we try to improve it and then later on when it is stable we will merge it back in to the go's official repo.

suntong · 2020-09-28T21:06:29Z

Have you tried turn on *Engine.Reload and leave Go html/template package unchanged @anton7r?

anton7r · 2020-09-29T20:17:03Z

Have you tried turn on *Engine.Reload and leave Go html/template package unchanged @anton7r?

yes, but thats not really viable to use on production because it will slow down rendering performance quite a bit

suntong · 2020-09-29T21:59:58Z

Ah, gotya. yeah, make sense.

Fenny · 2020-09-29T22:00:37Z

I'm still trying to fix the issue, but no luck so far 😕😵

edit: found the problem, expect a PR soon. ( keep you updated )

Fenny · 2020-09-29T22:16:23Z

@suntong, @anton7r this problem is fixed in v1.6.3, feel free to re-open if you encounter problems 👍

suntong added the ☢️ Bug label Sep 20, 2020

Fenny added the 🔍 Under Investigation label Sep 21, 2020

anton7r mentioned this issue Sep 21, 2020

Add test case for: Cannot Clone "layouts/main" after it has executed gofiber/template#48

Merged

Fenny added the 💡 Help wanted label Sep 27, 2020

Fenny mentioned this issue Sep 29, 2020

🩹 fix partial clone err gofiber/template#52

Merged

Fenny removed 🔍 Under Investigation 💡 Help wanted labels Sep 29, 2020

Fenny closed this as completed Sep 29, 2020

preslavrachev mentioned this issue Jan 17, 2023

Clarification Request: Why are template layout no longer being cloned? gofiber/template#216

Open

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

🐛 template/html: Cannot Clone "layouts/main" after it has executed #818

🐛 template/html: Cannot Clone "layouts/main" after it has executed #818

suntong commented Sep 20, 2020

anton7r commented Sep 20, 2020

anton7r commented Sep 21, 2020

anton7r commented Sep 21, 2020

anton7r commented Sep 21, 2020

anton7r commented Sep 21, 2020 •

edited

Loading

Fenny commented Sep 24, 2020 •

edited

Loading

suntong commented Sep 24, 2020

anton7r commented Sep 25, 2020

Fenny commented Sep 25, 2020

john-gold commented Sep 27, 2020

anton7r commented Sep 28, 2020

suntong commented Sep 28, 2020

anton7r commented Sep 29, 2020

suntong commented Sep 29, 2020

Fenny commented Sep 29, 2020 •

edited

Loading

Fenny commented Sep 29, 2020

🐛 template/html: Cannot Clone "layouts/main" after it has executed #818

🐛 template/html: Cannot Clone "layouts/main" after it has executed #818

Comments

suntong commented Sep 20, 2020

anton7r commented Sep 20, 2020

anton7r commented Sep 21, 2020

anton7r commented Sep 21, 2020

anton7r commented Sep 21, 2020

anton7r commented Sep 21, 2020 • edited Loading

Fenny commented Sep 24, 2020 • edited Loading

suntong commented Sep 24, 2020

anton7r commented Sep 25, 2020

Fenny commented Sep 25, 2020

john-gold commented Sep 27, 2020

anton7r commented Sep 28, 2020

suntong commented Sep 28, 2020

anton7r commented Sep 29, 2020

suntong commented Sep 29, 2020

Fenny commented Sep 29, 2020 • edited Loading

Fenny commented Sep 29, 2020

anton7r commented Sep 21, 2020 •

edited

Loading

Fenny commented Sep 24, 2020 •

edited

Loading

Fenny commented Sep 29, 2020 •

edited

Loading