[Bug]File Priority not working/complete propely

[Tseng]

Today i experienced for the first time (since 1.7.x) a weird bug in the priority system.

Usually when i download Torrents with many files inside it (Music Albums or Big files chunked into smaller rar archives), i always put priority higher on the first files. Especially important in case of music, so i can hear the first few songs while the rest is downloading.

Now today, with uTorrent 1.7.5 #4602, i noticed some weird behaviour. As always, i put the first songs 1-3 on high priority, songs 4-6 on normal priority and 7-13 on low. At the begin, it was as usual, uTorrent requested the chunks of the first two songs and downloaded it. But then suddenly when the files (1-3) got 95-97% completition, uTorrent started to download the other files with 'normal' priority. But, it didn't completed the first 3 files.

I let it go for a while, but nothing happend. The 'normal' flagged files got more and more completition, until songs 4-6 was ~95-97% completition and guess what? You're right! uTorrent started to download/request the chunks for the other files, flagged als 'low' (files 7-13), without completing any of the 1-6 songs.

I found this a weird behaviour, so i simply selected all 'low' flagged files, and choose the 'Don't download' Priority option (aka skiped). After a short waiting, uTorrent completed the songs 1-6.

So there is definitly a bug in this system, which needs to be fixed. Cause it completly voids the existance of this download priority system.

I'm not sure when this was introduced, all i can say, i never noticed it with uTorrent 1.7.2 (Betas and older versions). So it's most likely introduced with some of the later 3 releases

[Firon]

What was the availability?

[Greg Hazel]

uTorrent ignores the priority setting if pieces are rare elsewhere in the torrent. So for example if you had 3 files, and everyone set "high", "normal", "low", then the availability of every piece would be higher on the first file, and lowest on the last. At some point that rarity affects the piece picker, and people begin downloading basically in reverse order to correct for that.

This has two positive effects (aside from seeming to ignore your priority setting):

1) Pieces which are rare, and thus picked, will be less likely to fall off the network

2) Pieces which are rare, and thus picked, are pieces likely to be requested by other peers, so you will have something to send them (and therefore be unchoked by them)

[Tseng]

Well, it's not like the order 'reverses', it's always the next lower priority level.

I've made a few screenshots (and tested it with 1.7.2, but noticed that it has same behaviour).

I've put them into a ZIP file and uploaded. They are pretty self explaining. What you can notice is that, the files always go to around 85-96%, then basicly 'almost' stops (Takes like eternity to get the last percents). But once the 85-96% files are only left (other got finished or stoped by skip), the other files got completed in like 15 sek. (where before that it took 2-3 mins to get 2-3%).

I don't want this behaviour, because I usally use this to preview the downloaded files, while torrent is loading (or in case of a splitted CD to get CD 1 first, so i can install or burn it, before the other one is finished).

As for availbility of the torrent, it was pretty high with over 200 peers and enough leechers, so there i can't see a reason to overwrite the priority settings.

Problem with the files not finishing in the ordner i want them to finish is, that i can't preview it for 3 reasons:

1) In case of Movies (AVI ones to be more specific), ISOs and archives, a 98% finished file, is useless to me, cause it can't be unpacked, started or be watched.

2) in case of streaming media (MP3s, MPEG Movies, WMVs) i can't start it either, because the files are set to have .ut extension and can't be opened either (Dont want really to disable it, cause its usefull to determine if a file was finished downloading or not)

3) third and last reason is, that media player for example, usally won't open files, which are in use (i.e. downloading and have write access)

I'd like to see this behaviour changed in future updates, cause as it's now, it's pretty useless, cause the results are about the same as if all files have 'normal' priority (only full downloaded files are usefull!). Either by changing it or maybe add an option, which can be enabled to turn of it's current behaviour.

[biasha]

uTorrent ignores the priority setting if pieces are rare elsewhere in the torrent. So for example if you had 3 files, and everyone set "high", "normal", "low", then the availability of every piece would be higher on the first file, and lowest on the last. At some point that rarity affects the piece picker, and people begin downloading basically in reverse order to correct for that.

This has two positive effects (aside from seeming to ignore your priority setting):

1) Pieces which are rare, and thus picked, will be less likely to fall off the network

2) Pieces which are rare, and thus picked, are pieces likely to be requested by other peers, so you will have something to send them (and therefore be unchoked by them)

Hi, it is old problem and many people had written about it before. it is not about rarity.

It is about extremely slow peers who does not allow "high priority" file to be downloaded first.

I've just described it in detail in troubleshooting thread http://forum.utorrent.com/viewtopic.php?pid=556196

But my post was deleted and topic had been closed. I would revoke someone's moderation rights if i were administrator.

The problem i am talking about is the case when torrent data is available from a lot of peers. None of pieces can be considered "rare" because almost all seeds have 100% of data (with exception for few current downloaders).

But EVERY TIME when i download album of 10 songs (or 10 porn movies if you like) and want to preview/start it while downloading, i just cant!

High priority file is actually downloading first, but it is not completed first! Because all slow (modem?) peers are involved in uploading this high priority file to me.

So it is common to see 3rd 500Mb file already finished while the 1st priority is still 99% stucking for last 5 minutes with 5kb/sec rate peers (if you restart utorrent it will be finished in seconds).

Whole set of files will be downloaded withing 30 mins, there is no problem with it. But if i want to start with some (any!) by setting "high" priority to it - i still have to stare at 99% for few minutes...

[ciaobaby]

And this SIX year old thread needed resurecting because????