uTorrent Feature: Prioritize by File Order

A feature that probably has been around that I just discovered on uTorrent: Prioritize by File Order.  Apparently if the files in a torrent have sequential names like episode numbers for seasons of tv shows, that feature will automatically set the priorities for the files with emphasis on the first couple of episodes so that they get finished first.  I used to mess with the priorities manually for that, but this feature makes it so much easier.  To get to it, click on the torrent that’s being downloaded and go to the files tab.  Select all the files, right click and hit Prioritize by File Order.

Posted on January 28, 2011, in computer stuff. Bookmark the permalink. 8 Comments.

  1. Thanks for making it clear! :D

    I was aware of this function, but I wasn’t sure how to use it. So thanks for the instructions! :)

  2. How do you UNDO this (once done) to go back to the normal “rarest first” prioity ???

  3. Thanks. I did the same (reverted to normal).
    Setting the priority would best for well seeded torrents, especially for those having sequential episodes, but for torrents with availability on the lower side, normal priority, which implements the “rarest first” logic would probably be the way to go.

    • Ah sorry, I didn’t realize I replied to the wrong thread. My apologies.

      Yeah, it would depend on what you want. As far as I can tell, if uTorrent cannot get its hands on the high priority stuff, it’ll make do with the low priority stuff so as to be more efficient. So in a way, prioritizing by file order still has that base covered kind of. It might just be that uTorrent will go for the high priority piece with a slower dl speed rather than the normal priority piece with a high dl speed. I haven’t really done any research on this and it’s just what I would believe based on what I know, and it seems plausible.

  4. Here is a good debate regarding sequential downloaders (who use sequential priority) and non-sequential downloaders (who allow the torrent to use it’s own logic – which includes rarest first & piece priority) :
    http://forum.utorrent.com/viewtopic.php?id=29726

    I especially liked this comment :

    Sequential downloaders DEMAND only the next piece they don’t have. In a mixed torrent swarm environment, the odds of other peers having the piece they demand is pretty low …which means ONLY seeds will likely have it! That forces seeds to upload the same “early” pieces of a torrent multiple times to multiple peers, KILLING the swarm when seeds leave with a >4:1 UL/DL ratio and availability is still less than 1. Even having bt.prio_first_last_piece enabled in uTorrent causes this to a lesser degree, as other peers and seeds are forced to spend more of their upload bandwidth sending out the first and last pieces of the torrent to new peer arrivals.

    Also, if there’s multiple sequential downloaders, any 2 will never download from each other at the same time because at least one of the 2 will always want pieces the other doesn’t have. This causes BitTorrent’s tit-for-tat logic to fail miserably!

    Even a low percentage of sequential downloaders on a torrent, such as 10%, can cause a huge concentration of the “early” pieces to be repeated by other peers…because the only thing the other peers can download from them is the first few pieces, and then that may be all they can share too for awhile. The torrent swarm can end up stalling, and then the overall download speed often falls to no greater than the upload speed of the seed/s…even if the seed/s previously uploaded the torrent multiple times already.

    The damage that sequential downloading causes is very similar to having LOTS of hit-and-run downloaders. (They leave the moment it finishes downloading.) This is probably the leading cause of torrent death.

    • That was quite insightful, and that never occurred to me before. It definitely hurts the swarm, but at the same time, that phenomenon really only occurs in torrents with a sequential download and the only kinds I can think of right now are TV shows. For disc images with n parts, it doesn’t really matter which part gets downloaded first since all the parts are required at the same time anyway. But yeah, I can totally understand how that can kill the torrents that do face sequential downloading. There could also be other things that could potentially relieve the negative effects.

      Maybe the effect can also be mitigated slightly if multiple sequential downloaders start at different times. The ones that started early ideally would be uploading to the ones that started later on. Also, in the case of a TV show, where one episode contains some n pieces, peers could be uploaded different pieces at anyone time, so it does make it possible for two sequential downloaders share with each other – but only if they got different pieces of the same file and assuming that sequential downloading doesn’t mean downloading every single piece in order. I’ve always been under the assumption (I also didn’t confirm) that it was downloading the files sequentially and not the pieces, which makes a huge difference. I don’t know how one would judge whether or not one phenomenon would outweigh the other, but at least it’s not all bad.

      According to this post, http://forum.utorrent.com/viewtopic.php?pid=13269, the person in question uses sequential downloading, but is unable to stream his or her file while downloading, so it might really be the case that uTorrent purposefully does not allow a super front heavy download.

      For people who are after previewing the show while downloading, that is where sequential downloading by piece would start breaking the torrent. In a realistic scenario though, I have never seen my torrent downloads so concentrated to the beginning set of pieces. Not very often does my download speed go fast enough for me to stream it as I download anyway.

      Also if the torrent is popular, there are so many seeds that sequential downloaders would always have someone who found the piece they need anyway. Even if these downloaders do not share with the other sequential downloaders, the sharing does break down, but at least, it doesn’t kill it – so long as all the pieces can be acquired.

      Another effect that further mitigates the negative effect is that the other pieces in the torrent also get downloaded, so the download is not as “front heavy”. I don’t really have any numbers to show how “uniform” my download was, but again I’m not sure which effect dominates.

      There are definitely two ends to the spectrum, but in the end, it just really depends on what people want. If people are after downloading things in a sequential manner, then they will risk the negatives effects as well as the other effects that could mitigate it, but really, I can’t see a way to tell and people can debate all the want, but there might not be a conclusion that decisively wins over another. At the very least, people can be aware of what could potentially happen and just be knowledgeable about it.

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