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Show HN: A “living” Linux process with no memory

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Re: Show HN: A “living” Linux process with no memory

#41
post #24

Earlier quoted context omitted.

Can you write a program to tell if any given program is going to halt?

Tell you what: you give me time and money, and I'll work on this program. Keep giving me time and money until I tell you I've succeeded.

Can someone write a program to tell me how much money I’d need to give you?

Re: Show HN: A “living” Linux process with no memory

#42
post #33

Earlier quoted context omitted.

No "horrible problems" arise from Python 2 being used on the same system that Python 3 is on. The only problems are trivial, which was highlighted in the analogy.

I didn't say same system, I said same time. As in, trying to run one program with both.

Wouldn't occur in this case, as the script starts with:

    #!/usr/bin/env python2

Re: Show HN: A “living” Linux process with no memory

#43
post #24

Earlier quoted context omitted.

Tell you what: you give me time and money, and I'll work on this program. Keep giving me time and money until I tell you I've succeeded.

Can someone write a program to tell me how much money I’d need to give you?

Give me time and I'll tell you at the end how much money you need to give me.

Re: Show HN: A “living” Linux process with no memory

#44
post #42

Earlier quoted context omitted.

I didn't say same system, I said same time. As in, trying to run one program with both.

Wouldn't occur in this case, as the script starts with: #!/usr/bin/env python2

You're arguing against something I never said.

Yes, this file, completely in isolation, has no problem.

But people want to different pieces of python code together. If one or the other only works with a specific version, it becomes a problem when you try to combine them.

Therefore, best practice is to get everyone on the same version. We want to stop having to ask which version everything is, and facing the disappointment when things can't go in the same program. We want to get back to the situation where it's just 'hammer', and that's good enough for 95% of people.

Re: Show HN: A “living” Linux process with no memory

#45
post #24

Earlier quoted context omitted.

Can you write a program to tell if any given program is going to halt?

Tell you what: you give me time and money, and I'll work on this program. Keep giving me time and money until I tell you I've succeeded.

Sure, I'll just be giving you half your wage with each coming hour.

Re: Show HN: A “living” Linux process with no memory

#46
post #28

Did anybody try to run it? Python part of this PoC depends on python2 module "fuse", which in turn depends on "gunpowder", "a library to facilitate machine learning on large, multi-dimensional images". What is even going on here? $ pip2 install fuse Collecting fuse Downloading https://files.pythonhosted.org/packages/c3/f6/82777531d0dd0fa1d1b509258873f4b48e1ec702dcf0258214fafb474895/fuse-0.1.3.tar.gz ERROR: Packages i…

I think you want https://pypi.org/project/fuse-python/ instead. That python packages can and often do have different names than their corresponding distributables is ... not great.

I agree that it's terrible, though it can be nice in cases where a package ends up forked— for example allowing Pillow to be a drop-in replacement for PIL.

Re: Show HN: A “living” Linux process with no memory

#47
post #11

I've now seen a similar case multiple times in the wild - if a process has a thread in uninterruptible sleep (e.g., blocked on a bad disk or a stuck network filesystem) and you kill it, the process dies, but the kernel waits forever for that thread before informing the parent process. The parent doesn't get SIGCHLD, and wait() doesn't return. (So, for example, your favorite init/supervisor won't restart the process o…

I think lich fits well :)

Re: Show HN: A “living” Linux process with no memory

#48
post #33

Earlier quoted context omitted.

No "horrible problems" arise from Python 2 being used on the same system that Python 3 is on. The only problems are trivial, which was highlighted in the analogy.

I wrote this reply earlier and deleted it. Part of me feels like it's too far afield, but it's also kind of not, so I'll include it. It's what's on the top of my mind right now: --- I'm a volunteer teacher at a Girls Who Code club. We use Python. I spent the last class before the universe collapsed into Cornoavirus hell introducing the kids to the concept of functions. After introducing the concept, I asked the kids…

I saw this reply earlier! It was gone by the time I tried writing a response, but I don't feel like it's too far afield at all: it's a really nice response. (And thanks for doing that! It's always nice to see people volunteering for genuinely helpful things like this.)

It doesn't seem like it was your fault, and it's understandable that you're frustrated.

I don't, however, agree that anything written in Python 2 is contributing to that problem. Just because code exists doesn't mean it has to be used by other people, and this is a proof-of-concept obviously outside of the range of the class you were teaching.

It's the Python Foundation's fault, and it doesn't seem like anyone else's. Python 2 is nicer to write from some perspectives, and, for example, the idea of somebody who didn't like Perl 6's changes being told to write Perl 6 instead of Perl 5 or else they were being harmful doesn't really make sense either.

Re: Show HN: A “living” Linux process with no memory

#50
post #17
post #11

I've now seen a similar case multiple times in the wild - if a process has a thread in uninterruptible sleep (e.g., blocked on a bad disk or a stuck network filesystem) and you kill it, the process dies, but the kernel waits forever for that thread before informing the parent process. The parent doesn't get SIGCHLD, and wait() doesn't return. (So, for example, your favorite init/supervisor won't restart the process o…

Can/do supervisors poll for this situation? Seems like that should be possible.

Sure supervisors can be made to poll. But a supervisor won’t be able to do anything to recover from this.
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