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Cut down default Half Open connections?


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"Process Explorer" showed huge gaps in my upload/download transfer. uTorrend freezed during these gaps.

The problem was solved - thanks to the forum and Switeck - after changing half-open connections from 8 to 3.

Could it be a good idea to change the default value in the next release?

Many could suffer from this, without even knowing. I have a good machine (Athlon 3000, 2 GB mem), clean, running XP, lots of software, everything working fine.. So this could happen to many..

Changing the setting immedeately gives good results. Changing it back, immediately gives problems after some seconds.

I admit I run eMule at the same time, but I don't think it makes much difference.

Info: internet connection here is 10 mbit/s upload and 10 mbit/s download. Upload is permanent about 1 MByte/s. uTorrent uses about 5% CPU.

The intervals vary. uTorrent is working well from 10 seconds to 4 minutes. Than gaps occur from 1 second uo to 20 seconds. So at times it can be very bad: every 15 seconds a gap of 10 seconds.

And as many stick to XP, and don't turn Vista, it may be worthwhile to repair.

And if you don't know it, or don't use a similar program: "Process Explorer" is a small free Microsoft download. Run it > double click uTorrent > Tab Performance Graph > See the graph of Bytes I/O. The gaps are very visible.

Thanks for uTorrent! Small and very efficient! I don't even feel the need to look for anything else.

Grinn.. I would even do a TelSell commercial for you!.

Greeting from the Netherlands.

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These users are not so lazy. They just download uTorrent, and start using it. They may not care at all about fine tuning, being busy, and believing the program will work pretty well without that. And they may expect that.

Also there is no warning at the installation, saying: Hey, watch your settings carefully, because there can be serious trouble.

So I really do wonder, how many people have this problem, without knowing it?

On the other hand, if they suffer from it only a second every minute, the problem may not be that big. But here it was a lot more..

There might be a related problem. Since one year or so, checking my email in Outlook Express very often took a long time. Half a minute or so, or more. I couldn't fix that. But now the problem seems to be gone. Who knows the freezing uTorrent had an effect on my Outpost Firewall too..

And I don't know if just using a slightly more conservative setting will do the job? Default half-open connection was 8. But the problem already started to occur a bit at 4. So I had to set it to 3 to solve it completely.

Thanks for the reply!

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The default settings of uTorrent (as shown by Speed Guide) are really bad for most people almost across-the-board.

8 active torrents, 5 downloading torrents

4 upload slots, NO upload speed limit!

50 connections per torrent, 200 connections global

Even a 1 megabits/second upload connection isn't really "fit" to handle that many torrents at once unless they were really lacking in peers and seeds.

The lack of an upload speed limit almost guarantees a connection overload...and hatred of uTorrent by ISPs.

Even 200 global connections can make lots of consumer-grade networking software and hardware unstable.

8 half open connection limit (trying 8 new connections at once, possibly all the time) is yet another way to overload a line+computer...as you found out. :P

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Well, it looks more like uTorrent can't handle more half-open connections. It freezes. But it does not use much CPU or other PC resources, and does not overload the line. I have 10 Mbit/s up and downspeed, but even at lower speeds I got the problem. So the often innocent uTorrent does get suspected in this case.. Baby uTorrent on trial.. So perhaps Mum should do something..

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I'm still not convinced uTorrent's totally at fault alone on your system.

Though you DID mention running emule at the same time...which can also tie up/use up half open slots. Together they would probably exceed max limit at some point, even if individually set low.

Even them together may not totally explain it...for example, a networking driver can seem totally stable but have a hidden overflow bug that only occurs under heavy load when the buffer fills up.

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Switeck, you are right, so I did some experiments during an hour.

1. Switching eMule on/off during uTorrent use with half-open: 8.

It is hard to tell if there is any difference because the duration of good periods and of gaps vary too much. It is hard to compare, in the moving graph of Process Explorer, that gives a 10 minute overview in Bytes I/O. At first I thought, with eMule off, it solved half of the problem, but on second thoughts I am not so sure. In both cases there can be good working periods of 3 minutes, but also gaps as big as 25 seconds. Or 10 seconds good working, and a gap of a second. My guess is: there seems to be an influence (with eMule: shorter good periods and larger gaps), but I am not even sure of that. And look at this:

2. eMule off, and reducing half open connections in uTorrent.

Setting half open connections from 8 to 5 hardly made any difference. It looks a bit better, but the problem is still too much. But setting it to 3 completely solves the problem. So there is no difference between having eMule on or off.

3. Network card buffer?

I've got a simple network card 10/100, Realtek RTL8139/810x. I could change it, but in my ISP's system it takes at least an hour to get online again, so I leave that. But for instance: When I download files from websites, they sometimes come in at 3 or 4 MB/s. It is quite amazing to get a program of 30 MB (really Mbytes) in 10 seconds or so. This speed exceeds the speed I pay for, 'only' 10 Mbit/s. The ISP, who offers much higher speeds, normally cuts me off to 10 Mbit, but does not always do that. But my network card can handle 4 MB/s without any buffer problems. So I don't expect it to be the problem at uploads too. But indeed, you never know what the driver (or ISP) may cause. So the problem still might be personal..

4. Influence on other network apps? Yes!

To increase the problem I set half open to 30. The result is: good working periods of 3-7 seconds, and gaps of 25 seconds. This enabled me to look at the influence of gaps on other programs.

During gaps, I can't websurf or check mail!

Internet Explorer, Firefox, and Outlook Express, they all start up and run, but cannot connect during gaps!

This makes websurfing very annoying! I already have that problem for a year or so. I suspected filesharing to consume al the bandwith, but even at lower speeds the problem persists. I suspected the ISP cutting down speed, if you fileshare too much. But now it seems to be these gaps to be the problem!

Next, I put uTorrent upload speed to unlimited. Suddenly it shows capable of 2 MB/s upload! (having Half Open at value 3) uTorrent still uses only 5% CPU. And guess what? Websurfing and checking mail still is rather fast!

5. Firewall?

Does not make a difference. The problems persist.

* Conclusion?

The default setting of Half Open Connections of 8 can produce a problem, that might be called big, because it affects not only up/down speeds in uTorrent, but also websurfing in an annoying way, without a clear indication there is something wrong. (so you don't fix it.)

Many people may have this problem, without knowing it, so should be fixed.

The cause may be unknown, but changing the setting does the trick.

* Different solution?

There is a utility (Lvllord) to increase the maximum of half open connections, that is limited in Windows XP to 10. You can set it to 50. I tried and rebooted, just to see what it did? But it changed nothing. The problem still occurred at the value of 8. Also at lower speeds, as it did before. And as before, changing to 4 still gave very small gaps every 3 minutes.. And setting it to 10 gives huge gaps, as it did before. (btw: is using Lvllord to set to 50 a good idea?)

I started to look at Windows Event Viewer > System log. There are some TCP/IP warnings (4226) about too many half open connections, in previous days. I rebooted now, and again got one 4226 warning, even now half open is set to 50..

* Suggestion for users?

It's fun: download Process Explorer here, at the bottom of the page:


Unzip it, and run the Exe.

In Process Explorer, click the process uTorrent.

And in the new window click Tab Performance Graph.

Watch the I/O Bytes graph, and look for gaps after a few minutes.

Please report it here. That may show how many people have the problem.

Note: uTorrent has such a graph too. But it does not show the gaps, because it is frozen at those times.

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I don't understand what you are referring to. But there is a severe problem, certainly now it affects websurfing. The cause is unclear. It looks like it is a uTorrent problem.

And it is uncertain how many people have the problem? It might be XP related, but most people use XP I think.. So it is not just some minor group. And the only moments you really notice there is a problem is, when you click in uTorrent at the wrong times.

And now many people may have it (unnoticed), and slow websurfing is really annoying, the question merely is how to find out if this occurs a lot, or what to do to fix it?

Lowering the default HOC to 3 does solve it, but may not be the finest solution..

So the 'Feature Request' in fact was, to have another look at this..

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Grinn.. "YouTube configurations from hell.." I'll instal 4 edonkey clients, and 6 torrent clients to get real fast speeds, pooring everything out of my bandwith. And then come back to you to solve some issues. And then I'll expect some quick and polite answers, or else go to a bitcomet forum to complain about you.. grinn.. :-)

But in this case uTorrents default HOC setting causes problems, and can only be solved when set from 8 to 3. That could mean, there is something wrong with uTorrent. The system here is good and clean, updated etc. So I just ask to have a good look at it, take a good graph tool for that, and see if the problem shows, or can be reproduced. It could be a bug..

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They don't have symptoms like freezing a few seconds.

And I don't have their problem with off-line status of trackers..

But thanks! I'll keep watching..

It's kind of exiting. And certainly a new way of not making money.. :-)

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The word 'Gap' here ment: No traffic at all during seconds.

I did Not mean these usual spikes or variations in the stream. There is not a problem, as long as there is any traffic to be seen at every moment. Normally You'll see a contineous stream at the bottom of the grid of "History Bytes I/O", whatever spikes may do.

But the 'Gaps' I ment are very obvious. You'll immediately notice it. Suddenly there is no traffic at all. So during these seconds nothing is green. The line is as flat as a sea horizon for some seconds. If this happens often, the whole picture looks like lonely green mountains at a sea horizon, drifting to the left.. (Periods with traffic = green mountains with spikes. Periods without traffic = a flat line.)

B.t.w. the real problem is, uTorrent freezes for seconds, and websurfing too. The gaps in Process Explorer only are an indication uTorrent freezes. It symply doesn't respond for seconds, if you click in it. The menu bar may become white.

Thanks for reporting opsknight!

If interested, you could raise HOC, and wait a minute or so to see if the problem occurs in Process Explorer. First from 8 to 10. Then to 15. Then to 20. At 20 the problem is really huge here: only traffic at 10% of the time. Don't forget to put it back to 8.

[edit] Don't set HOC to 3, if Process Explorer does not show problems at the setting of 8.

@Littelfire.. "Blumchen"? Haha.. Grusse aus Holland! Du weisst schon: dort wo wir alle verruckt sind, aber zunachst kein Problem damit haben!

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I actually ..LOL..uhm had my HOC set to 1000 before coming across a few threads here. I was trying to fix the TCP/IP connection limit issue I was getting. I noticed no difference from 1000, 8, or 3. . I also stressed test seeding about 20 torrents and downloading 1. Was still seeing overall speed of 1mb down and 125 kb up and process explorer was normal for the few hours i watched it.

I was using WIN XP Pro and ut1.8. The only issues I had was reaching my connection limit and utorrent would die overnight and stop talking to the trackers.

Last night for fun I set up Vista and ut1.8 using HOC at 8 and the speed settings reccomended from here. I downloaded a moderately seeded torrent, and got 450mb down and 35 kb up. I got home from work just now and everything is still running, the 19.5gb torrent was finished, I had uploaded 750mb with just 1 ot 2 leechers and my eventlog was clean.

Gonna play around some more. So far IMO the app seems smoother on Vista, but who knows why, could just be a better driver for my wireless N adapter. Oh yeah Im wireless too.

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(HOC to 1000?? I get this feeling I won't rest until 1000 people try to reach me at the same time, and I can deny them all, having my own streams flow.. Probably I am developing an new pervert variant of digisex: Doctor help me: I can't go, unless my HOC setting is above 500.. grinn.. )


Problem partly solved..

Lowering the amount of started torrents to 20, setting HOC to 8, is working fine with hardly any gaps. Starting more torrents seems to increase the amount of gaps. But it seems to depend on the the actual amount of HOCs at the time. During good periods there are 3 to 5 or so. (I check that amount by often pressing: Menu bar > Help > Show statistics) But just before a gap occurs, the amount of actual HOC's is about 8. So it might be uTorrent freezes, when a 9th connection tries to establish.

This is more likely to be the problem, than the amount of torrents. Even when I start all of my 140 torrents, sharing 60 GB data, there is no problem as long as the actual amount of HOC's is beneath 8 (like 3-6).

Thanks Opknight! Since you called sharing 20 torrents "stressing", I did this research. But sharing 20 torrenst isn't exactly stressing.. And I don't know what it exactly was, you were sharing? If it was grandma's great cookie recepies, perhaps there weren't too many people trying to connect to those.. :-)

But thanks, it still is informative, 1.8 can work well under XP and Vista, tested with Process Explorer..

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I think the half open connection limit may only apply to peer/seed connections. uTorrent's attempts to contact trackers to do tracker updates may not count...so periodically uTorrent may go over 10 half open connections if you have enough torrents running and/or torrents with LOTS of trackers...especially trackers with the exact same update intervals.

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Problem solved!

I used LvlLord to raise the HOC-limit in XP from 10 to 50: all problems gone!

Even setting the uTorrent HOC-limit to 30: no problem and no gaps!

Also no delay during websurfing or checking email.

No problem running eMule at the same time.

LvlLord's patch for XP users can be downloaded at: www.lvllord.de

I don't know if there are any issues using that. But Microsoft says the limit of 10 HOC's was only built in to prevent fast spreading of some viruses, or something. Other OSses do not have a limit. So it doesn't seem to harm, raising the limit to 50.

I don't understand, because I did this before, without any result. I used LvlLord and rebooted, but perhaps it didn't do the job, or I made a mistake at the XP-warning, that systemfiles were about to change. That warning has to be cancelled. And after that, getting a new question, again it must be allowed. I might have made a mistake there.

But perhaps it must be done twice. The LvlLord site says in june 2006, that version 2.23d (=current version) still works with Microsoft's new version of TCPIP.sys, but must be 'reapplied'. So must it be done after XP's auto-update installed a new version of TCPIP (that's for sure!). But perhaps they also mean, you have to run their patch twice (?) In all cases, better run the patch again after rebooting, just to see if the current HOC-limit really has changed to 50.

And better run the patch now and then, because at auto-update Microsoft may replace TCPIP.sys, giving you a HOC-limit of 10 again. (certainly happens when SP3 is installed)

Comment on a Dutch forum: If using torrents, your internet will go "like thick shit through a funnel", with a HOC-limit of 10. That was exactly what Process Explorer showed here..

Perhaps the uTorrent crew could email Microsoft, if there are plans to increase the limit? I already saw complains. But I don't know where to mail to myself.. But if you do, nad Microsoft does not reply, or is negative about it, consider this:


Perhaps when uTorrent is installed on XP, the user can get the message, better to increase the HOC-limit.

Perhaps build in LvlLord's patch (39 KB). Or build in a download link, giving some clear instructions, including what to do at XP's two warnings, and recommending to run it twice to check if it is done..

Opknight, thanks for your remark! I checked Event Viewer again because of that, and still saw warnings, while I thought the XP HOC limit was set to 50. That made me think twice, finding out it still was set at 10!

My Event viewer doesn't show warnings anymore, so LvlLord may solve your problem too..

Switeck also thanks, then you too made me think..

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I don't have a slowness problem with my half open connections set at 1-8.

But that's because my uTorrent isn't firewalled.

If firewalled, uTorrent's ONLY means of getting connections is via outgoing connections made at the rate allowed by uTorrent's half open connection limit.

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