275324 - Page load of weather radar loop requires 100% CPU, much time

Status: RESOLVED EXPIRED

(Firefox :: General, defect)

Description

[Stuart Strickland]

Upon clicking "Loop" from National Weather Service (Pittsburgh, PA) to receive a
series of 10 .GIF images of local radar, FF 1.0 pegs the CPU until all 10 images
are downloaded.  CPU then drops to normal and the animation plays as expected.  

Reproducible: Always

Actual Results: CPU pegs at 100% for the roughly 90 seconds required to load 10
images.

Expected Results: CPU pegs at 100% for 10 or fewer seconds, as in Moz 1.7.3 and IE6.

Steps to Reproduce: 
1. Start Windows Task Manager
2. Start Firefox 1.0
3. Go to National Weather Service-Pittsburgh page showing local radar, a single
GIF file: http://www.erh.noaa.gov/radar/latest/DS.p19r0/si.kpbz.shtml
4. Note the time and CPU utilization to load this one image, typically 30
seconds for the first access, 10 seconds for a refresh.
5. In left pane, under "Base Reflectivity", next to "Short Range", click on
"Loop"; URL is http://weather.noaa.gov/radar/loop/DS.p19r0/si.kpbz.shtml
6. Note the time and CPU utilization to load the 10 images, typically 90 to 100
seconds.  

While the elapsed time can be expected to be 100 seconds, the CPU should not be
pegged at 100% for that time.  In both Moz 1.7.3 and IE6, elapsed load times
were comparably 90 to 100 seconds, but 100% CPU lasted only about 10 seconds.

Software environment:
Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.7.5) Gecko/20041107 Firefox/1.0

Microsoft Windows XP [Version 5.1.2600]
(WinXP Pro Version 2002, SP2)

java version "1.4.2_04"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.2_04-b05)
Java HotSpot(TM) Client VM (build 1.4.2_04-b05, mixed mode)

Hardware environment:
Dell Dimension 4100 desktop, Intel 930 MHz Pentium 3, 384 MB RAM, 56K dialup.

I compared the load times with Mozilla 1.7.3 and I.E. 6.0.  CPU pegs for much
longer, and elapsed time is also much longer.  [Soon-To-Be] Attached are screen
shots froom Windows Task Manager of both Performance (CPU utilization) and
Networking (bandwidth utilization) for, in order, FF 1.0, Moz 1.7.3 and IE6.

Similar bugs: Bug 254285, Bug 268096, Bug 264740, Bug 265832; this is not an
exhaustive list.

History: This has been around since FF 0.7, possibly earlier.

Comment 1

[Stuart Strickland]

Attachment: Screenshot of Windows Task Manager showing Performance graph

For WTM-Performance: Each vertical line represents 12 seconds.
FF 1.0 load of loop starts at about 1/3 of the way across.  

Mozilla 1.7.3 then follows.  First, a load of the single latest radar image,
which causes a very narrow spike to 65%.  Then all 10.	Note that the peak is
about 10 seconds; a pair of minor spikes follow, but these are irrelevant,
related to my shifting a couple of windows around.

IE 6.0 then follows with the same sequence: a brief spike when loading the
single image, then roughly the same 10-second peak.

Comment 2

[Stuart Strickland]

Attachment: Screenshot of Windows Task Manager showing Networking graph

For WTM-Networking: As with the Performance graph, each vertical line
represents about 12 seconds.  Horizontal alignment should be very close to that
one.

FF 1.0's 10-image load is above the words "Network Utilization".

Moz 1.7.3's 1-image load is above the right-most of the pair of "0%", about 25
seconds.
Moz 1.7.3's 10-image load begins above the words "Bytes Sent".	It took over
two minutes, but with a mainly idle CPU.

Ignore the spike above the words "Byte per...".  (That was IE loading my home
page.)

IE's 1-image spike is a very narrow spike directly above the right-most "0".
IE's 10-image load begins just after that, and is about 30 seconds wide.

Comment 3

[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
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you still believe we should implement it, please visit the URL of this bug
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If it is not a problem any longer, you need take no action. If this bug is not
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Thank you for your help in this matter.

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Comment 4

[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.