jacksum MD5SUM takes too long with encrypted home

[peterzay]

Ubuntu 10.04 jacksum would take about 15 seconds to display the MD5SUM in a text file in Nautilus. The "look inside" feature of Nautilus for text files shows the sum in the upper left corner of the text icon. All Update Manager updates are applied and the system is current.

I have installed Ubuntu 10.04.1 with encrypted home on a more powerful machine and the same process takes about 2 minutes. All Update Manager updates are applied and the system is current.

Both tests were launched by right click using nautilus-actions.

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: jacksum 1.7.0-2
ProcVersionSignature: Ubuntu 2.6.32-40.87-generic 2.6.32.57+drm33.23
Uname: Linux 2.6.32-40-generic i686
Architecture: i386
Date: Tue Apr 17 10:25:36 2012
Dependencies:

EcryptfsInUse: Yes
InstallationMedia: Ubuntu 10.04.1 LTS "Lucid Lynx" - Release i386 (20100816.1)
PackageArchitecture: all
ProcEnviron:
 LANG=en_US.utf8
 SHELL=/bin/bash
SourcePackage: jacksum

[Dustin Kirkland  (kirkland)]

How big is the file?

What kind of hard drive (spinning platter or SSD?)

[peterzay (peterzay)]

The file is the i386 ISO for Ubuntu 12.04 beta 16-apr-2012, about 699 MB.

The hard drive, in both cases, is a 5400 rpm traditional spinning disc. The regular drive is 160 GB while the encrypted one is 320 GB.

Both are in Lenovo SL500 laptops.

Is there any way this could be a java issue?

[peterzay (peterzay)]

I tested the Ubuntu native md5sum program on the encrypted home and got record fast completion, just a few seconds.

This has to be a java issue.

I will investigate this weekend and report back.

[peterzay (peterzay)]

On the regular non-encrypted home machine that runs jacksum fast, the following java related products were found in Ubuntu software centre:
- openjdk java 6 runtime
- openjdk java 6 web start
- openoffice.org base

I uninstalled the runtime. The 3 products above were removed. The following packages were also removed:
- default-jre
- libaccess-bridge-java
- openoffice.org-base
- openoffice.org-java-common

After all this, jacksum was tested and did not work. Closer inspection revealed jacksum was no longer installed.

I installed jacksum and redid the md5sum test on the same ISO file mentioned above. It took several minutes to complete, just like on the encrypted home machine.

So to sum up:

1. The name of this bug should be changed to: jacksum MD5SUM takes too long without java installed

2. jacksum dependencies need to include java

3. workaround for this problem is to use native Ubuntu md5sum program which works very fast

[Anuradha Weeraman (aweeraman)]

Just to clarify, Jacksum is written in Java, so it depends on Java. It won't run without the JVM present and the package dependencies specify that.

If performance is critical, I would suggest that you use alternatives such as md5sum and shaXsum as they don't depend on the VM and have much less runtime overhead, and you may be able to eke out some performance.

[dino99 (9d9)]

That version is no more supported; and no expecting backport as it only concern 'security' problem.