KTorrent repeatedly crashes

I have started experiencing a strange problem in Suse 11.3 KDE. Till recently everything as going well but since last few days Ktorrent has started behaving strangely. All of a sudden KTorrent crashes and KTorrent-- the KDE Crash Handler gives following details:
Executable: ktorrent PID: 12911 Signal: 11 (Segmentation fault)

How to get rid of this problem permanently. I am using KTorrent Version 3.3.4


How is the rest of your system, is anything else affected leading up to your crash?

If your system has slowed and even experienced lockups or if your network connections grind down to zero, increasing your TCP Buffers will likely fix your problem, if you’re experiencing degraded network connectivity changing your TCP Congestion Control algorithm can help.

See my posts (tsu2) in these recent threads

How to Persist TCP Congestion Control algorithm change?
Slow uploadrate


Rest of the system is fine, may be till now I have not experienced the probable problems you are indicating… (may arise later… only time will tell)
I am sorry, I could not understand anything in these two posts you have mentioned. Its beyond my computer knowledge.

If your apps very suddenly crashes without warning, it’s probably not related to my other posts.

In a nutshell regarding my other posts,

Today’s Linux kernel is optimized for “normal” network use, which generally means small, quick file transfers typical of activities like web surfing and email messages over hard wired network connections. If you do anything else like maintain active connections to a multitude of other machines (like torrent apps), transfer very large files(even torrent chunks can be megabytes and not kilobytes in size), network connections are degradeable or faulty(Turn a microwave on near your WiFi access point or connect in the next room through a wall, use satellite or use a wireless phone data network) or operate across a vast, unreliable network (like the Internet), then changing the Congestion Control algorthm can (not guaranteed) help.

At the very least, based on what I’ve observed anyone running a torrent app which maintains massive numvers of active connections (and Ktorrent seems to be very agressive in maintaining even inactive connections), TCP Buffers should be enlarged to accomodate the resources needed for so many connections. Or, restrict the number of connections within your torrent app.

More detailed info in the web article I’ve promised in the links I provided…


I have reduced the two options:
Maximum connections per torrent
Global connection limit

Lets see how this behaves now. I have also noticed that when I increase the upload speeds, it crashes more frequently.

Please try to run KTorrent from terminal and see what error pops up when it crashes. Moreover in the past I had problems with BitComet crashing (it’s another bittorrent client). It turned out that it was caused by one of the private trackers I was using to download as the tracker required to disable DHT and peer exchange and I had both turned on. Be sure to check if You have those settings enabled or disabled.

Oh one more thing that comes to mi mind. I’ve read that the KTorrent client that comes with openSUSE is crippled and has got DHT and peer exchange disabled. Maybe You are encountering a bug with this crippling so You may want to try for example Deluge or Opera bittorrent client if You won’t find the problem.
ktorrent.org - View topic - ktorrent opensuse

Best regards,

As a user of Ktorrent,

  • Bad trackers can cause all torrent file communications to hang, but does not cause the entire application to crash (not just hang but to cause an exception). Solution is to always purge/disable all bad trackers. Since Ktorrent does not identify whether a tracker is a first or lower tier tracker, I can’t blanket recommend disabling all but one working tracker assuming that all trackers contain the same Peer info.

  • By default Ktorrent supports and has enabled DHT and Peer Exchange. In fact, I suspect this is why Ktorrent is so aggressive maintaining connections even to inactive clients, Ktorrent may be doing that to update DHT and Peer Exchange data often.


I had enabled DHT in the begining itself (since I installed Suse) although I have no knowledge whatsover it does being ‘on’ or ‘off’.
About Deluge, I had few problems with uploading (long time back). Have never tried Opera client.
Have used QBittorrent in Ubuntu and Kubuntu (in the past). Liked it much, but then I shifted to Suse KDE and it had inbuilt KTorrent.
Presently I have* limited my upload speeds*, although it takes more time to achieve a ratio of 1:1, but at the same time it keeps running (has crashed only once since today morning).


Good to hear you may be experiencing improvement. Your situation reminds me of a situation years ago when I saw a problem perhaps the same as yours that my ISP at the time didn’t throttle/manage upload speeds as well as download and similarly experienced degraded throughput. I found at that time and have ever since always carefully watched my upload speeds to manually throttle never to exceed specified ISP upload max speed, and this applies no matter what OS you may be running.

As for DHT, a quick lookup should reveal that it stands for “Distributed Hash Table” and like Peer Exchange is a “trackerless” technology that turns every Peer into a Tracker, able to pass on to other DHT peers torrentfile data. The bottom line is that today configured accordingly torrents can work without trackers… It might take awhile to “discover” a peer with the torrentfile info needed but once that is accomplished everything else happens fairly much normally.