Jump to content

uT1.8.3 faulty upload slot handling when upload slots=1


Recommended Posts

(Note uTorrent v1.8.3 beta 15104 is what I tested on, but it's not the only uTorrent version I deem likely to have this problem. uTP and Teredo/IPv6 connections are NOT ACTIVE during this test! They would likely make the condition worse.)


With 3 seeding torrents started, the first 2 are set to NORMAL priority but only have 1 peer, the last one has LOW priority and 9-20 peers. Upload slots per torrent set to 1, with Use additional upload slots if upload speed <90% checked. Upload Speed Limit set to 120 KB/sec, which uTorrent (outside of this test) has no problem sustaining for hours on end.

Occurring every 2 minutes the upload speed takes an almost complete nosedive, often falling below 60 KB/sec sometimes below 30 KB/sec. Roughly 10-50% of the time is spent running at considerably less than max upload speed (120 KB/sec) as a result.

The torrents with only 1 upload slot are often not uploading to their lone peer, despite being higher priority than the torrent with LOW priority that has 9-20 peers.

The torrent with 9-20 peers often starts multiple upload slots, then every 2 minutes drops those upload slots...then 5-30 seconds later starts a different set of upload slots. Apparently this is "Use additional upload slots if upload speed <90% checked" in action. Because of the simultaneous timing, global upload speed nosedives when this happens.

Optimistic Unchoke behavior seems to be used even when there's only 1 upload slot and 1 peer...which means roughly every 30 seconds to 2 minutes, uploading to the current peer is stopped and a "new peer" (the same one of course!) is chosen again a few seconds later, but 1 minute may be needed to get up-to-speed again. These 1-peer torrents have no problem constantly uploading when I raise their upload slot max to 2 or more. This behavior seems to occur on multiple torrents at the same time aggravating the low upload speed problem.

The predominate use of Optimistic Unchoke upload slots when upload slots per torrent is set to 1 seriously reduces how much a uTorrent peer uploads back to the peer that is uploading the most+fastest to it. (tit-for-tat) This makes torrents more vulnerable to sequential downloaders (because optimistic unchoke forces the uploader to upload the same thing over and over again to multiple peers), hit-and-runners (because optimistic unchoke "favors" no one, so even those that upload little-to-none...gain a large chunk of the uploader's bandwidth), and hostile poisoners (because optimistic unchoke jumps around too quickly, often giving poisoners time to add bad data to unfinished pieces.) All of this combines to cause many torrents to become unseeded.

Example pictures...

Running awhile with 1 upload slot per torrent (but allowing more if upload speed <90%):


What happens when changing from my normal settings to 1 upload slot per torrent:


And one of the 1-peer torrents quits transferring:


I deem it likely that this person's problem was caused (at least in part) by this bug:


This bug still occurs with the latest uTorrent v1.8.3 beta (build 15589).

Link to comment
Share on other sites


This topic is now archived and is closed to further replies.

  • Create New...