270679 - Download manager CPU usage is very high when download size of file is unkown

Status: RESOLVED DUPLICATE of bug 270312

(Toolkit :: Downloads API, defect)

Description

[Simon Werner]

User-Agent:       Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.5) Gecko/20041107 Firefox/1.0
Build Identifier: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.5) Gecko/20041107 Firefox/1.0

This is similar to bug #260860 (but it was filed for Windows XP).

When files get downloaded of unknown size, the download manager displays a fancy
scrolling bar that moves along the window, when it gets to one end it starts
again at the other end. I found that this requires a lot of CPU usage.

Reproducible: Always
Steps to Reproduce:
1. Download 3 files of unknown size.
2. Observe CPU usage (I used `top` under Linux) increase with each additional
down load.

Actual Results:  
CPU usage higher than expected for files of unkown download size. CPU usage
normal for files of known size.

Expected Results:  
CPU usage should remain about the same as normal.

I think that if the update rate of the scrolling bar is reduced (for a download
of unkown size), the bug may disappear.

Had 14 tabs open (none had animations).
Processor is a Celeron 1.6 GHz and for each download (of unknown file size)
firefox takes up another 30% (or so) of CPU usage. It seems like XFree86 is also
doing a lot of work, most likely due to drawing the scroll bar so often.

I will attach some more reports after this.

Comment 1

[Simon Werner]

Attachment: CPU usage details for different download type

Comment 2

[Thomas Swan]

I'm seeing this with Win32 but in a more general sense.   I'm using a slower PC
with 1GB of ram, and I have tracked part of the performance problem back to
screen repaints in the download manager.   If you enlarge the download manager
to full screen 1600x1200x32 then the system starts pausing inexplicably and very
frequently even if no downloads are in progress.  With three or four downloads
running it will sometimes bluescreen the PC.  The fade-ins are complete torture
for the system CPU wise.

The same happens, but no blue screen, on other faster computers (WinXP 2.4GHz)
running at high res.

Comment 3

[Joao Fraga]

I confirm this on Firefox 1.0 for Linux. The CPU is very high.
This only happens on files of "unknown size", which leads me to think that the
problem is in the animated progress bar.
Example URL:
  
ftp://penguin.dq.fct.unl.pt/suse81axp/KDE/update_for_8.1/base/kdebase3-3.2.3-8.alpha.rpm

Comment 4

[Gereon Steffens]

I confirm this for Firefox 1.0.4 on WinXP.

Easy way to reproduce: go to www.zanik.pl/filmy, find the three links that begin
with "Pro Tips" (about 2 thirds down the page). Now right-click on each of the
links and select "save link as". Firefox will eat all available CPU, as long as
the download status window is visible. Minimizing or closing the window will
reduce CPU usage to normal levels.

Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.8) Gecko/20050511
Firefox/1.0.4 

Comment 5

[Gervase Markham [:gerv]]

This is an automated message, with ID "auto-resolve01".

This bug has had no comments for a long time. Statistically, we have found that
bug reports that have not been confirmed by a second user after three months are
highly unlikely to be the source of a fix to the code.

While your input is very important to us, our resources are limited and so we
are asking for your help in focussing our efforts. If you can still reproduce
this problem in the latest version of the product (see below for how to obtain a
copy) or, for feature requests, if it's not present in the latest version and
you still believe we should implement it, please visit the URL of this bug
(given at the top of this mail) and add a comment to that effect, giving more
reproduction information if you have it.

If it is not a problem any longer, you need take no action. If this bug is not
changed in any way in the next two weeks, it will be automatically resolved.
Thank you for your help in this matter.

The latest beta releases can be obtained from:
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Seamonkey:   http://www.mozilla.org/projects/seamonkey/

Comment 6

[Gervase Markham [:gerv]]

This bug has been automatically resolved after a period of inactivity (see above
comment). If anyone thinks this is incorrect, they should feel free to reopen it.

Comment 7

[:Gavin Sharp [email: [e-mail]]]

*** This bug has been marked as a duplicate of 270312 ***