Deno•3y ago

Deno.run Strange Issue

I use

Deno.run

Deno.run

stdout/signals/etc a lot, but this behavior is beyond my current debugging abilities

have a command

nix eval ...

nix eval ...

which works fine in a python subshell, and on the commandline. However, Deno.run with piped stdout makes it hang indefinitely. To be explicit, in this block:

process.status().then(callback).catch(callback)

process.status().then(callback).catch(callback)

the callback doesn't run until a

.kill()

.kill()

is used (SIGHUP/SIGINT/SIGKILL). Tested on Deno 1.29.4 and Deno 1.22.0 for good measure.

What is even more strange is trying to bypass the problem with hackery also fails.
All of these round-about execution methods (translated to Deno.run) also hang indefinitely:

```
bash -c '[command]'
```
```
bash -c '[command]'
```

bash ./file_with_command.sh

bash ./file_with_command.sh

bash -i ./file_with_command.sh

bash -i ./file_with_command.sh

In particular the

bash -i

bash -i

method not only hangs, but also exclusively makes it so that ctrl+C, ctrl+D, and even ctrl+Z are ignored; I have to kill the deno process from another termial.

Env:

bash -c env

bash -c env

prints out the EXACT same env vars for Deno/Python/CLI
Cwd: deno/python/cli all have the same working directory
Interactivity: running it with

deno repl

deno repl

has been the same as

deno run

deno run

Piping:
Manually closing the stdout pipe doesn't work/help.
Removing

stdout: 'piped'

stdout: 'piped'

, makes command not-hang (but defeats the point).
Adding

stderr: 'piped'

stderr: 'piped'

still causes a hang.

I don't even know what else could be possibly causing a difference (Deno & Python code attached as comments)

jeff.hykinOP•2/13/23, 12:19 AM

Here's the deno code (does need nix: https://nixos.org/download.html ):

And here is the python for comparison

And for good measure here is also Ruby code, which also doesn't hang

ioB•2/13/23, 3:35 AM

I haven't had a chance to look into why this might be hanging, but I will point out that

Deno.run

Deno.run

is being deprecated in favor of which has an objectively clearer api. I will look into this when I get the chance

AapoAlas•2/13/23, 5:56 AM

Deno.run

Deno.run

does have some hanging issue as well. If memory serves then one way around it is to all the three outputs of the run, not only status but stdout and stderr as well.

IioB I haven't had a chance to look into why this might be hanging, but I will point ...

jeff.hykinOP•2/13/23, 1:18 PM

I was looking into that but are there docs for Deno.Command? I expanded every section on https://deno.land/api@v1.30.3 and ctrl+f still returns nothing

It also doesn't seem to exist on 1.29.4

Screen_Shot_2023-02-13_at_7.17.33_AM.png

AAapoAlas `Deno.run` does have some hanging issue as well. If memory serves then one way a...

jeff.hykinOP•2/13/23, 1:25 PM

wow... this actually works/doesnt hang. Thanks @aapoalas

Jjeff.hykin I was looking into that but are there docs for Deno.Command? I expanded every se...

AapoAlas•2/13/23, 1:56 PM

It's probably still under the "unstable" checkbox. IIRC the PR stabilising it has only just been merged or is about to be.

ioB•2/13/23, 2:58 PM

It is going to be part of iirc