[Bug 2119394] Re: Uninstallation hobbled by gzip

[Dougga]

A possibility of a root cause.
So I updated the bug with the actual screenshot of btop instead of a political statement.  [I left the original for your amusement]
Take a look at the disk statistics.  I have a modest root partition.
I found that the process of uninstalling the app fills the root partition very very slowly.
After 30-40 min the root partition started approaching 100% utilization and I killed the process.
What I'm thinking is the snap architecture has a backup feature that uses the root partition to create backups of the snap app that is being removed.  In the case of steam, with several games attached, this backup is utterly immense.   In this case I was removing Oblivion: Remastered, Skyrim, Fallout 4 etc....  Perhaps hundreds of gigs.  Perhaps there is insufficient logic in this backup procedure and it was attempting to use gzip to reduce the size of the backup.  It seems it would have failed, rendering the machine unstable or unusable - I'm betting on the latter, but am not brave enough to let it go through with the process.

I used the Disk Usage Analysis program that comes with this distribution
to determine where on the root partition the file was being placed.  I
could not find anything growing using this tool, but the partition was
clearly filling up. based on BTOP.  This snap function seems to render
Ubuntu unstable.  What I would do generally to mitigate this
vulnerability is to create a dedicated partition for the location snap
uses for these backups, but I can't figure out how this is done, nor
what resources specifically are used.

All of this suggests an architectural/design flaw in the snap
application that undermines the whole OS.

Possible changes:
- Alter base installation to create an optional partition for this high disk-utilization snap functionality, so the OS is not undermined if the partition is filled.
- Add logic that calculates when everything is too large to manage and drop snap backup procedure when it would crash the machine.  
- In the case there is adequate disk storage on the root partition, calculate the time required to process the backup and give the user an option to abort this backup to save an hour of time.

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to apport in Ubuntu.
https://bugs.launchpad.net/bugs/2119394

Title:
  Uninstallation hobbled by gzip

Status in apport package in Ubuntu:
  New

Bug description:
  I'm uninstalling Steam (with a two or three applications installed under steam.
  I expect an uninstallation process to take a couple of minutes max.
  What I'm seeing is somewhere between odd and suspicious.
  It's taking  45 minutes to uninstall Steam, and this is on a machine with an Intel Core i9 14900KF (32 cores), 64GB RAM, and a very fast SSD.
  BTOP is showing gzip slammed for processing power and snapd taking up a bit.  Nearly all cores are idle and it would appear from my untrained eye that gzip is limited to 2 cores which seems to be the root cause of this problem.  I see two cores being used significantly: both between 35% and 75% changing with every refresh of btop.  

  I find it hard to imagine this is not a bug given the absurd time it
  takes to remove an application.

  Ubuntu 25.04 fully updated
  Steam latest/stable 1.0.0.83
  Expectation: Quick removal of software package from system.
  What happened: An interminable wait as gzip is doing gawd knows what.  It shouldn't be used in a software removal process.  This is the suspicious part.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/apport/+bug/2119394/+subscriptions