Show HN: A “living” Linux process with no memory • Hacker News Board

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

#21

Post by [deleted] » Thu, Mar 26, 2020, 3:31 PM UTC

state_less wrote: post #19

stevemk14ebr wrote: post #12

Earlier quoted context omitted.

we're programmers, anything can be done with enough time or money

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

[deleted]

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

#22

Post by klyrs » Thu, Mar 26, 2020, 3:33 PM UTC

rat9988 wrote: post #5

ebg13 wrote: post #2

It's 2020. You couldn't have done this in Python3?

He could. You also could have done it in Python3, and you still can.

"He" is named Isabella.

https://github.com/izabera

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

#23

Post by yjftsjthsd-h » Thu, Mar 26, 2020, 3:34 PM UTC

zelphirkalt wrote: post #13

hsnewman wrote: post #8

Can this be implemented in Go?

Not sure whether this is serious, or some sarcastic comment, hinting at all the "blablabla implemented in Go" posts. EDIT: Aaaand there is the crew!

Surely rust is the preferred option for that? Go hasn't been nearly as vocal in my experience.

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

#24

Post by cwp » Thu, Mar 26, 2020, 3:35 PM UTC

state_less wrote: post #19

stevemk14ebr wrote: post #12

Earlier quoted context omitted.

we're programmers, anything can be done with enough time or money

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.

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

#25

Post by xenadu02 » Thu, Mar 26, 2020, 3:36 PM UTC

btown wrote: post #17

geofft wrote: 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.

Also curious why the kernel can't abandon the thread since the process is dead anyway; set a bit in kernel space so on the walk back from the syscall it bails out instead of trying to return to userspace.

That doesn't solve the kernel thread being stuck forever problem. I'm not sure what the fix is there... is it bad drivers with no timeout mechanism? I don't know how they'd do that unless the kernel IO is all async anyway. Just tearing down the kernel thread seems likely to leave the locks abandoned in bad states.

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

#26

Post by klyrs » Thu, Mar 26, 2020, 3:36 PM UTC

hsnewman wrote: post #8

Can this be implemented in Go?

Normally I'm not a fan of people nitpicking language choices... but in this case I upvoted because this is a really weird "stupid program trick" and I'm curious what languages support such shenanigans.

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

#27

Post by yjftsjthsd-h » Thu, Mar 26, 2020, 3:36 PM UTC

state_less wrote: post #19

stevemk14ebr wrote: post #12

Earlier quoted context omitted.

we're programmers, anything can be done with enough time or money

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

With enough time, sure! [0][1]

[0] Disclaimer: may take slightly longer than heat death of current universe.

[1] Alternative solution: https://m.xkcd.com/1266/

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

#28

Post by kees99 » Thu, Mar 26, 2020, 3:39 PM UTC

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 installed from PyPI cannot depend on packages which are not also hosted on PyPI.
  fuse depends on gunpowder@ git+https://github.com/funkey/gunpowder@721718b6569b47a2f5d5d6633c76c85f779e25c7

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

#29

Post by notpeter » Thu, Mar 26, 2020, 3:42 PM UTC

kees99 wrote: 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…

Pretty sure they meant to depend on python-fuse not fuse. The former is python bindings to libfuse.

https://github.com/libfuse/python-fuse

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

#30

Post by michens » Thu, Mar 26, 2020, 3:42 PM UTC

kees99 wrote: 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 it's meant to depend on the fuse-python (https://pypi.org/project/fuse-python/). fuse is something else