Go: x/playground: Game Of Life play example fails to compile on golang.org due to out of memory error

[epeay]

Please answer these questions before submitting your issue. Thanks!

What version of Go are you using (go version)?

1.11.1 as reported by the server.

Does this issue reproduce with the latest release?

Not relevant. Server-side issue.

What operating system and processor architecture are you using (go env)?

Not relevant. Server-side issue.

What did you do?

https://play.golang.org/p/jibIOKi7wqW

What did you expect to see?

The game of life

What did you see instead?

go tool compile: exit status 2
fatal error: runtime: out of memory

The example does run (I tested on 1.10.3 locally). It just doesn't run on the golang.org site, likely due to a restriction on the back-end environment that's doing the compilation.

If the environment is what it's supposed to be (whatever that is), and the example just needs to be tweaked to use less memory, I'd be interested in taking care of that and sending a PR.

[ALTree]

and the example just needs to be tweaked to use less memory,

I very much doubt this is the case. I suspect this is related to the bad caching on nondetermistic error issue the playground had: #26926. Not sure why it's still happening, in theory it should be fixed. I don't know if the fixed playground was deployed.

[agnivade]

/cc @broady @andybons

[ysmolsky]

Right now playground checks errors in the response.Events slice, that is for successfully built programs:

// Runtime error strings that will not be cached if found in an Event message.
var nonCachingRuntimeErrors = []string{"out of memory", "cannot allocate memory"}

But in our case it failed to build the program , response.Errors contains OOM message, response was cached and returned. We should do the same check for response.Errors too.

[andybons]

@katiehockman

[katiehockman]

Thanks for the extra context @ysmolsky. Looks like the original change fixed some issues, but not all.

@ALTree to answer your question, yes it was deployed shortly after the change was merged.

I'll assign this to myself and hopefully send out the fix very soon.

[gopherbot]

Change https://golang.org/cl/144297 mentions this issue: playground: prevent caching memory-related compile time errors

[dmitshur]

Commit golang/playground@d134d7d391d04bb6c1c7cd8abb1f3eec872c7de6 has been deployed now. Please let us know if the issue occurs again.

[epeay]

@dmitshur The issue is still happening live now...
https://play.golang.org/p/jibIOKi7wqW

Now that we know what the issue is, I can see that changing a single character in the code sample results in successful code execution. Clearing that cached execution result (the error) should get this working on the site again.

[katiehockman]

The cache will need to be cleared out first. Then it shouldn't pop up again.

On Fri, Oct 26, 2018, 7:14 PM Elliott Peay [e-mail] wrote:

@dmitshur https://github.com/dmitshur The issue is still happening live
now...
https://play.golang.org/p/jibIOKi7wqW

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[andybons]

The cache has been cleared. I don't see an error in the playground response any more.