Extreme CPU usage at 99% download of individual files

[Jason Newman]

qbitorrent 2.4.8 - 2.4.11
regardless of whether download first/last piece first is selected - at 99% qbit attempts to download anything and everything but that last %. the cpu pegs at 100% until that last 1% is downloaded sending my LT's temperature gauge to 81/85 (has forced an overheat shutdown twice). the download rate will drop drastically at 99% from say 60k down to .01 to 3k.
When I say tries to download anything and everything, it will even download an adjacent file that has expressly been set to "not downloaded" instead of try that last 1%. Typicically to get it to download I have to uncheck all other files, pause the transfer and then continue. when it reaches 99.9% it drops to 10's 100's of bytes almost exclusively. No matter what I do this won't change much. Checking/unchecking the file gets it to jump up to 1-3k sometimes but not always. Essentially, where I should get that last % in 1-3 minutes, it can take up to 30 minutes. (and much longer on very large files)

I have noted that when I pause/restart the transfer while it's in this state, the processor doesn't peg until it starts downloading (while it's uploading only - it's normal utilization), the instant it starts pulling down instead of just uploading- 100% utilization.

As soon as that last percent is done - cpu utilization goes back to normal immediately.

Frequently (almost always) when the file first gets to 99.1-99.9% (it varies, but usually closer to 100), it jumps backwards to 97.3% (always-like the meter was inaccurate and it just noticed) It doesn't exhibit the speed issues till it gets to the "real" 99%.

speed limits make no difference. file priorities make no difference. default options, specified options etc etc. In fact I just got lucky and noticed at one point that the 'pegged processor' issue started at the real 99% - the 'fake' 99% was obscuring when the problem would start.

Aside from this, I find qbittorrent to be a fantastic program and despite this nagging issue - I won't use another product over it.

[Christophe Dumez (hydr0g3n)]

Could you please file the issue there: http://code.google.com/p/libtorrent/issues/entry

qBittorrent is a GUI for libtorrent-rasterbar. There is no way that this issue can be caused by qBittorrent. When copy/pasting your description, please add the libtorrent version number (currently missing) as this is very important here.

[Jason Newman (csub-woofer)]

rasterbar0.14.10-2+ according to aptitude

Apologies for the delay. I've spent the last *&)(* day and half hacking a new version of BOOST into place so I could compile one of the recommended versions on the download page.

I'm now using 0.15.4 after a successful configure/make/install but have not been able to observe the described problem as no files are yet 'in the zone' - I will make additional notes once that has occurred.

If my issue is more appropriately addressed to the libtorrent-rasterbar maintainers, I'll gladly call this 'handled'

[István Kondor (kondor)]

FWIW, I can confirm this on Lucid but not Maverick which means libtorrent-rasterbar - 0.14.12-0ubuntu1~lucid is the bad one and libtorrent-rasterbar - 0.15.4+svn.r5052+really0.15.4-0ubuntu1~maverick works fine for me.

[István Kondor (kondor)]

Sorry, I was wrong, this also affects v2.5.1 thus the corresponding libtorrent version.

[Christophe Dumez (hydr0g3n)]

Do you have all use 64bits? I'm now able to reproduce it since I switch from 32bits to 64bits. It might just be a coincidence but I thought I would confirm with you guys.

[arvid Norberg (arvid-cs)]

could someone who can reproduce this issue profile the client at the point where it uses 100% CPU?

something like an Instruments capture (on mac) would be awesome.

[István Kondor (kondor)]

Yes, Chris, I do use 64 bit, but I have the same problem on a 32 bit machine. Large torrent, extremely slow download (<1k), so I stopped it for now. That machine, however, is running Lucid, if it matters.

[Christophe Dumez (hydr0g3n)]

Apparently, this patch for libtorrent should fix this issue.

I will apply it to my PPA packages tomorrow.

[Christophe Dumez (hydr0g3n)]

People using my PPA will get the fix through updating today. Please confirm that it works.

[Damir Butmir (d4m1r2)]

Hi, I am also currently having this issue with v2.6.9 on Ubuntu 11.04 (natty, 32 bit).

It does not consume 100% of my CPU, but it goes up slightly. However, the main issue is the speed drops DRASTICALLY at 99.9% (from 1mb/s to 10b usually) and the status will say downloading for an hour or 2 and will eventually complete. I first thought this was has some "hash recheck" but I have that related feature disabled. A workaround (thats works for me atleast) is to stop and restart the torrent. It usually finishes then once the speed picks up again.

I think this should be looked into....