Open Radar

 
Summary:
In Safari 8.0.2, if 1-4 downloads are started, they proceed normally. Bandwidth is divided between the four but they all make progress.

If a fifth download is started, all downloads stop making progress. The total bytes downloaded for all downloads stalls. Activity Monitor shows that the bandwidth spike caused by the downloads drops to near zero.

Worse, when this happens, Safari is unable to connect to any web sites at all. If I type a URL in the address bar and press enter, the site never loads.

At the same time, Activity Monitor shows that the "Safari Networking" process consumes 140-150% of a CPU.

Stopping downloads does not restore normal operation. The only fix is to quit and re-launch Safari. (I'm filing this in Firefox because Safari is currently unable to connect to any sites).

Steps to Reproduce:
1. Launch Safari 8.0.2 and begin multiple file downloads.


Expected Results:
Downloads would begin and continue until complete.

If a large number of simultaneous downloads are requested, either of the following would occur:

a. All downloads would begin, but would download more slowly due to the high demand
b. Some downloads would begin while others would pause until some in-progress download had completed, so that the total number of downloads in progress remained below some threshold.

Actual Results:
When the number of downloads exceeds a threshold (more than 4 in my testing), all downloads stop, Safari is no longer able to connect to any sites, and "Safari Networking" consumes excessive CPU. All of these conditions persist until the user quits and relaunches Safari.

Version:
OS X 10.10.1 (14B25), Safari 8.0.2 (10600.2.5)

Notes:
I'm attaching a sample of the Safari Networking process obtained with Activity Monitor, and a couple of illustrative screen shots.


Configuration:
I don't know if this problem is new with 8.0.2, I don't often need to download a bunch of files like this.

Attachments:
'Archive.zip' was successfully uploaded.