Extracting zip archives in mc is horribly slow

[halfbeing]

I have just extracted a zip archive using mc and it was horribly slow. The archive was 108MB with a lot of source code and documentation, i.e. a mainly small files, and it took many minutes. At one point the ETA was over 30 minutes, at which point I cancelled the operation and started again, but it remained very slow. Typically the same operation would take unzip a matter of seconds.

There was no noticeable CPU load coming from the extraction operation.

ProblemType: Bug
DistroRelease: Ubuntu 13.04
Package: mc 3:4.8.3-10
ProcVersionSignature: Ubuntu 3.8.0-30.22-lowlatency 3.8.13.6
Uname: Linux 3.8.0-30-lowlatency x86_64
ApportVersion: 2.9.2-0ubuntu8.3
Architecture: amd64
Date: Sun Sep 29 14:02:03 2013
EcryptfsInUse: Yes
InstallationDate: Installed on 2013-08-22 (37 days ago)
InstallationMedia: Ubuntu-Studio 13.04 "Raring Ringtail" - Release amd64 (20130424)
MarkForUpload: True
SourcePackage: mc
UpgradeStatus: Upgraded to raring on 2013-09-24 (4 days ago)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Szabolcs Szasz (lunakid)]

Just adding some more weight to this:

Unzipping a 20 MB Drupal update package (50 megs raw), and it's been going on for like 5 hours now!... :-o :)

All vanilla stuff (DigitalOcean's Drupal8 droplet image + apt-get update + install mc):

mc: 4.8.11
Ubuntu: 14.04.4 LTS (GNU/Linux 3.13.0-88-generic x86_64)

top - 19:13:17 up 7:02, 2 users, load average: 1.27, 1.30, 1.31
Tasks: 78 total, 4 running, 74 sleeping, 0 stopped, 0 zombie
%Cpu(s): 59.3 us, 29.1 sy, 0.0 ni, 11.5 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
KiB Mem: 501756 total, 424256 used, 77500 free, 81140 buffers
KiB Swap: 0 total, 0 used, 0 free. 166104 cached Mem

  PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
32136 root 20 0 10400 1688 608 R 50.2 0.3 0:00.24 unzip
32134 root 20 0 37312 8752 2100 R 43.9 1.7 0:00.28 uzip
32137 root 20 0 24808 1436 1060 R 6.3 0.3 0:00.01 top

(mc sometimes shows up in the top 10, but nothing suspicious).

Thanks, and good luck!

[Yury V. Zaytsev (zyv)]

It's horribly slow if you have lots of small files. This is due to how extfs is implemented (a shell script is called for every file), so there is nothing we can do about it (other then re-implement extfs system completely by adding support for group operations).

[lnxusr (bjwest)]

How about fixing it without rewriting extfs? After 19 minutes extracting and a reported 30 more to go, I quit MC and unziped the file from the command line. Took less than a minute, so MC is definitely hosed in how it unzips.

[Yury V. Zaytsev (zyv)]

> How about fixing it without rewriting extfs?

So what's your plan? I've explained the cause of the problem, and why it requires a rewrite above.

[lnxusr (bjwest)]

Four years on and this is still an issue. Arc took less than 20 seconds to extract a file with 20277 files, while MC is almost two hours in and still only 89% complete. This is from the same file to the same drive. Something's seriously wrong with the extraction code in this application, and needs to be fixed.