Fiber: 馃悰 template/html: Cannot Clone "layouts/main" after it has executed
Fiber version
v2.0.2
Issue description
Continue from https://github.com/gofiber/fiber/issues/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
suntong
All 16 comments
i have the same issue
anton7r
on 20 Sep 2020
im looking into it!
anton7r
on 21 Sep 2020
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
on 21 Sep 2020
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
on 21 Sep 2020
i think removing this from the golang/go/html/template/template.go and refactoring the code would fix the issue
anton7r
on 21 Sep 2020
The question is why is an escapeErr set in the first place, maybe this is something we can solve on our end.
Fenny
on 24 Sep 2020
The question is why is an
escapeErrset 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.
suntong
on 24 Sep 2020
The question is why is an
escapeErrset 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?
anton7r
on 25 Sep 2020
I have some time tomorrow to debug this issue, I will post updates here 馃憤
Fenny
on 25 Sep 2020
Hello, so far I'm only getting this error if
*Engine.Reload == false
logol
on 27 Sep 2020
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.
anton7r
on 28 Sep 2020
Have you tried turn on *Engine.Reload and leave Go html/template package unchanged @anton7r?
suntong
on 28 Sep 2020
Have you tried turn on
*Engine.Reloadand 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
anton7r
on 29 Sep 2020
Ah, gotya. yeah, make sense.
suntong
on 29 Sep 2020
I'm still trying to fix the issue, but no luck so far 馃槙馃樀
edit: found the problem, expect a PR soon. ( keep you updated )
Fenny
on 30 Sep 2020
@suntong, @anton7r this problem is fixed in v1.6.3, feel free to re-open if you encounter problems 馃憤
Fenny
on 30 Sep 2020
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Most helpful comment
@suntong, @anton7r this problem is fixed in v1.6.3, feel free to re-open if you encounter problems 馃憤