Download speeds die off to 0-1 kb/s on large torrents

[pikee10]

I'm having a problem with maintaining downloads for a prolonged period of time on very large torrents (my current download is ~40 GB). Everything starts fine and behaves like I expect it to, but when left alone for a couple hours, the download will die out. The task is still running though, and usually still happily uploading at >500 kb/s. Stopping and starting the torrent doesn't usually work, but closing and re-opening bitcomet altogether will bring it back to normal, after taking a minute to re-connect as usual. Strangely, the dying out seems to take longer if I mess with the torrent before it dies out, like selecting/deselecting different files and changing the priority levels on them. I found one other thread by searching here that had a similar sounding problem, but the user in question was a service member abroad with a very unstable connection and he was trying to run 20-30 tasks at once. The only replies addressed the obvious problems and the standard configuration, which I've done.

On that note, I'm using 1.36, my port is forwarded/listen port is green, running Windows XP. I also have a windows 7 machine that I run on, but never encountered this problem there - but probably because I don't use that one for huge downloads, just very well-seeded ~1GB, sometimes up to 5. I'd always just left my global upload limit unlimited before with seemingly no ill effects (maybe a slight slowdown in web browsing), but after reading here for a bit I did the speedtest thing (25/5 Mbps Verizon FiOS fiber connection) and set the upload limit to 550 kB/s. However, the limit doesn't seem to be taking effect as my upload is still pretty steady at 600 with spikes higher than that. Also, how important is it to choose a listen port in that range from the settings guide? I've got the current port forwarded, and I'm not too keen on going back into my router if it's not really all that necessary. I can get screaming fast downloads on well-seeded torrents already.

Thank you for your time

Side question - should I be able to run bitcomet on two seperate computers behind the same router at the same time? Is this a bad idea even if possible? And if it does work, will they transfer between each other even having the same IP? I know this is a weird "why would you want to?" kind of question, the idea would be to switch which computer I'm using for the download while it's in progress, using the one that started to seed the one taking over and get it caught up quickly.

Edited September 3, 2013 by pikee10 (see edit history)

[The UnUsual Suspect]

How many connected peers have 100% of the files? and are the majority of peers at the same level you are (or less)?

[pikee10]

there have been 2-4 seeds consistently. I just stopped and restarted again. This time I wasn't uploading either. Didn't look at the peers before stopping, but it's already picked up 3 seeds.

Another side question, what does the yellow frowny face next to the IP address mean in the peer list?

Edited September 3, 2013 by pikee10 (see edit history)

[The UnUsual Suspect]

are the majority of peers at the same level you are (or less)?

[pikee10]

Currently have 2/8 peers. I'm at 93%. 2 of the peers are 0-1%, the rest range from 78-97. i'm getting basically all of my download from one guy who's at 87%. I'm getting almost nothing from the seeds or the guys who are getting most of my upload. Next time it stalls I'll note what the peer situation looks like.

I should point out that this isn't the only torrent this has happened on, just the first time I've thought to ask on the forums about it.

[pikee10]

Alright it died again. I'm only connected to one peer now, who is at about 80%

[The UnUsual Suspect]

This looks like a simple case of a weak torrent, the only seeders present don't appear to have enough bandwidth available to provide you with better speeds. The reason you were uploading much more than downloading is because new peers who join will download from you until they catch up the the level you're at, then their performance will suffer just like yours. The reason your download seemed to improve when you were disabling files is because in doing so you were deleting data then when you enable them again you would redownload the same pieces you just deleted. It's really not a good idea to experiment with disabling files in a torrent, this feature should only be used if you never intend to download those files.

[pikee10]

That's what I meant really. I wasn't doing it just to increase the speed, I was disabling files as the previews became available and I decided I didn't want them. Interacting with the torrent was seeming to help me stay connected, similar to what the guy in the old post I found said. I can understand a weak torrent causing speeds to slow as seeds/peers drop off, but I don't get why I don't seem to re-connect when more come available. Once it drops off, it stays there until bitcomet is restarted, at which point I get pretty much full speed back instantly.

[greywizard]

It's very possible that one or more of the seeders in the swarm use "initial seeding" which means you will see a new piece from that peer only when it receives confirmation that you already uploaded back in the swarm the last piece it fed to you.

This is a technique meant to lower the amount of data the seeder needs to upload in the swarm and to "force" other peers to seed back or "stay on the sideline".

However, in very small swarms this doesn't work really well and might give results such as you see.

If that's the case, there isn't really much you can do from your side, except arm yourself with patience.

As for your second question in the first post, Bitcomet doesn't have such a feature. uTorrent has implemented it a while ago (and it's still there AFAIK - it's called "local peer discovery") and it might do what you want, but I've never tested it personally, so I can't say how it works.