659435 - Download Manager sometimes shows download complete when it's not.

Status: RESOLVED INCOMPLETE

(Toolkit :: Downloads API, defect)

Description

[algotechie]

User-Agent:       Mozilla/5.0 (Windows NT 6.1; rv:2.0.1) Gecko/20100101 Firefox/4.0.1
Build Identifier: Mozilla/5.0 (Windows NT 6.1; rv:2.0.1) Gecko/20100101 Firefox/4.0.1

At times, when the built-in Download Manager (let's call DM) finishes downloading a file and shows the slide notification that the download is completed, the file is actually shorter in size than the full size that the DM was displaying while downloading it (with something like "<time> remaining - <downloaded size> of <full size> (<download speed>)"). Most frequently, this happens when a new page (with loads of content; or a few new pages) is loaded while the download is going on. Well, simultaneous loading of many an element may slow down the downloading but there's no reason the download should fail. Instead, the DM should keep the minimum necessary bandwidth/speed reserved to it so the downloading continues at the expense of the pages loading a bit slower.

That, and when the DM knows the full size of the file, why does it mark a download as completed (without showing the "download failed" error) when the size of the portion it has downloaded is smaller than the full size?

I would much rather expect the downloads to complete (actually complete), but if that's yet to take time, at least the DM should know that it's not yet downloaded the whole file.

Reproducible: Sometimes

Steps to Reproduce:
1. Be on a relatively slower Internet connection. The problem does occur on high-speed connections but much less commonly.
2. Start downloading a file, preferably a large one.
3. Open a content heavy page that would demand multiple simultaneous requests, like a page with lots of images or auto-playing videos. (Sometimes, you might need to open more than one of such pages.)

Actual Results:  
The DM breaks the download and reports that the download finished successfully.

Expected Results:  
Preferably, the DM shouldn't break the download. Or if it does, at least it should display an error notification (not that that would make the user cheer over the situation).

The add-on DownThemAll gets it right - It never reports a download as finished when it's not. I see no reason why the built-in DM cannot do the same when it keeps a record of both the parameters (the size downloaded and the full size).

(Some servers do not support the DM's that download the file in multiple parts; so I have to use the built-in DM for those files.)

Comment 1

[Stephen A. Goss]

This happened to me with official Firefox 5.0 build on Ubuntu 11.04 (64 bit). Downloading a 2.4 GB file at about 600KB/sec. It stopped and reported complete at 2181168549 bytes.

Comment 2

[Wayne Mery (:wsmwk)]

Download mgr is revised.
Do you still see this problem when using a current version?

Comment 3

[algotechie]

This happens randomly and of late, I've not had needed to download something using the built-in download manager. Will be able to say something later if it happens again.

Comment 4

[Phoenix]

Resolved per whiteboard