Comment by godelski
15 hours ago
As a Linux user I've hated VSCode's ssh. There's lot of annoying things that make it harder to admin for. Like it doesn't pick up the MotD, preventing me from showing users important messages. I've found that it also doesn't reuse sessions (at least by default. TBF, neither does ssh) and I'll find that there's just dozens of open sessions over months from users. I literally had to write a script to boot people...
It would be one thing if the plugin was just a wrapper and people were still expected to know ssh but the plugin abstracts away all that and is intended to make it a "use VSCode on remote machine" tool. So it needs to do more than just handle creds, otherwise it creates a divergent experience while making people think it's just ssh
> There's lot of annoying things that make it harder to admin for.
It also (AIUI) tries to walk the entire file tree, so have fun with NFS (auto)mounts.
It also amounts to letting off fork bombs: we set up limits for a maximum of 256 process per UID, and regularly get folks asking "what does this 'cannot fork' message mean?": it mean you're trying to DoS the system.
> we set up limits for a maximum of 256 process per UID, and regularly get folks asking "what does this 'cannot fork' message mean?"
The max limit on 64 bit systems is what, 4,194,303? So if you have over 16,000 users per VM this limit makes sense, otherwise it just seems user-hostile.
Every process takes some memory and other resource, yes a stale process will pretty much all end up all paged out and not massively in the way of active processes, but they still aren't entirely free so it is more than a bean-counting number.
Yes, under Linux (and most unix-a-like systems) small processes are cheap to bring up and tear down which is why we create them so much, and it is not uncommon for complex interactive commands and bits of shell scripts to create several¹, but these are all likely to be short-lived so a limit of 256 certainly doesn't seem to be obscenely low to me.
What could it be doing that requires 256+ processes to be kept around for a prolonged time?
--------
[1] made up example: comparing filtered content of two gzipped files and sending the result through a script to send alerts by mail if certain things are found would be 7+ (2x gzip, 2x or more grep, diff, bash, mail or curl depending on what service you are sending alerts through)
> The max limit on 64 bit systems is what, 4,194,303? So if you have over 16,000 users per VM this limit makes sense, otherwise it just seems user-hostile.
And yet we still regularly loads of >100 on our 64 core HPC login codes, and swap is regularly used even with 96G of system memory (we have per UID memory limits too).
What's hostile is the VSCode (and Codex and Claude) makers developing tools that basically DoS a system because they assume it will operate only on single-user machines.
(And WTF are you doing that you're forking 256 processes? We have quite a few expensive HPC nodes: use those to build, not the damn login nodes.)
Honestly every developer needs to increase those default limits, they are too low for modern development... So you are just crippling them and a proof of that is they keep getting this error while in their regular workflow
I don't even hit 256 on my desktop with a shitton of things open and 75 firefox sandbox processes, much less on a remote server. What in heaven's name are you doing to cross 256?
(Also this isn't a default limit.)
And it doesn't work on BSD, and fails in an opaque way when it tries.
I don't think I've ever paid attention to a MotD on any of the servers I had a ssh access to... what do people put there?
You know, typical admin stuff
Ah, I see. Our admins typically understood that users were being given disk quotas precisely so that they could use that disk space, but that's probably not a universal stance.
5 replies →
> I don't think I've ever paid attention to a MotD on any of the servers I had a ssh access to... what do people put there?
And then we get "Is the system down?". Yes, the fucking system is down.
Right?
Like, I used to, but it was in the early 1990s.. People look at them now?
Next I'll be asking people to finger me to get my availability ..
We have the servers role, you can derive that from the name obviously, but we do have hosts which as the same naming scheme, but slightly different roles. There's when the last Puppet run happened and what it applied (and who authored it). Depending on the host type there's also active/standby, warnings for production hosts or information about increased log level on things like sudo.
It sounds like a lot, but it's fairly compact and really helps when you need to absolutely sure where you are and you have eight terminal windows open.
And it’s really opaque. Would be fine if it were an open source package but there’s a lot of mystery behind how it’s implemented.
I don't find it that opaque. Even without trying to deobfuscate the obfuscated source code which Microsoft ships (I haven't tried but it wouldn't be hard) a lot of details about how it works become obvious just by reading its logs.
Of course, it is a pity Microsoft doesn't open source it. But there are some well-maintained open source alternatives, e.g. https://github.com/jeanp413/open-remote-ssh and https://github.com/F1yingWhite/fast-remote-ssh (I haven't got around to giving either of them a go–but I really should.)
They will never open source it. For the same reason Pylance etc. aren't open source and MS tries hard to prevent them to be used in VSCodium. Every one of their open sourced projects contains a closed source plug that MS can pull at any time that is one of the features that gives the project its unique selling points.
Exactly! Like if I'm admining a server what am I supposed to do? Message on a big slack channel and have everyone ignore me? It's easy when people are just logging in through normal ssh as I can put a big bright warning message on their screen that they can't ignore.
Also, timeouts...
Also, does anyone know if VSCode supports mosh?
Could just put this in /etc/bashrc.
Assuming your users use the integrated terminal regularly
5 replies →
I have looked for mosh support for a while and not found anything. It would drastically improve the connection experience in VSCode. My terminals never disconnect anymore, but the Code popups about your sessions needing to be restarted has drastically reduced my usage.
1 reply →
To use mosh vscode would have to do OCR because mosh transmits images of the terminal
1 reply →
The one this that is better than just SSH+Tmux+Vim, is that if your latency is higher than 30-50ms, since VSCode's SSH agent streams the files to your computer, the typing experience feels snappier. When you work half a continent away from where the servers are, it makes life nicer.
> I'll find that there's just dozens of open sessions over months from users
We've had the same issue with our local HPC; a few login nodes serving hundreds of users at a time, and each login node used to get swamped by these dangling SSH sessions/servers. They also wrote a script that shuts down all sessions once a day to save the login nodes.
Well, it's better than JetBrains Remote Development which opens a new SSH connection every second.