possible related with #38855

/cc @andybons @toothrot

I don't believe that #38855 is related to this issue, as that issue is specific to faketime, not to the timeout in running programs.

I don't see why this program should timeout reliably on the playground, or at all. The running time on the playground on my laptop is around 300ms. I'll see what I can figure out.

There are several places we can write that message. In local testing, it seems like the particular run timeout that is printing it is this one: https://github.com/golang/playground/blob/0298bc862cef82adf756a5d2c5b5b48920b84009/sandbox/sandbox.go#L357

This tells me that the sandbox container has the binary, got it on time, and the binary itself is just taking too long to execute for some reason.

The example in #38855 is this one https://golang.org/pkg/os/exec/#CommandContext and if you try to run it, it has the same behavior.

Same for this

https://golang.org/pkg/net/http/httptest/#Server

https://golang.org/pkg/net/http/httptest/#NewTLSServer

https://golang.org/pkg/net/http/httputil/#DumpRequest

https://golang.org/pkg/net/http/httputil/#DumpResponse

and I suppose many more

This issue could be due to networking being disabled in sandbox containers in #25224, as even trivial tcp servers don't work on the playground in my testing.

@psampaz It's a nuanced difference, but this issue is not related to #38855. #38855 is caused by someone expecting a timeout inside of their program to occur, which will not happen as expected unless the fake clock is moved forward. On the playground, there is a slightly different version of the Go runtime ("faketime") that implements a fake clock, which helps make snippets repeatable, along with other features that are playground specific. https://golang.org/cl/192740 has the implementation, if you are curious.

This issue, #39016, is the program on the playground timing out, and never finishing execution. It's also a timeout, true. However, it is not a timeout inside the user's program, but a timeout of the playground waiting for the user program to finish.

The server references you posted are helpful, and also confirm that this is a generalized issue with networking in sandboxed containers.

Actually, the fact that it sometimes works leads me to believe it could be an issue with faketime, but certainly not in the same way as reported in #38855.

Maybe related: a simple program with both net.Pipe() and time.Sleep() fails in playground with "timeout running program".
Share link: https://play.golang.org/p/IoBh7drjhkT

package main

import (
	"net"
	"time"
)

func main() {
	net.Pipe()
	time.Sleep(time.Millisecond)
}

If I delete either line, the problem does not occur.
Despite the error, if I add other code to interact with the net.Conn object returned from net.Pipe(), they are functional.

It often fails even with the simplest Hello World:

I am getting the same message on the playground, while I am doing the go Tour. I am in the section where they explain Methods

Same problem on Go Play Space https://goplay.space/ ...

Same problem on the Go Playground tour.

😐

The same with play.golang.org/compile

This was caused by a temporary outage and has been resolved (see #44537).