Picotorrent: 100% CPU when (re)connecting with Windscribe VPN

Created on 12 Apr 2018 · 7Comments · Source: picotorrent/picotorrent

Start PicoTorrent
Connect using Windscribe VPN via the Windows application (you can try it for free)
As soon as the connection is established, PicoTorrent starts using 100% CPU (for one thread).

If Windscribe is already running when PicoTorrent is started, everything's fine, but a disconnection/reconnection results in the same thing.

OS: Windows 10 x64 1709

bug

Source

ltGuillaume

All 7 comments

Confirming the behavior - I'll see what I can find!

vktr on 15 Apr 2018

Shoot I just found out that this also occurs with qBittorrent! That'd probably make it a libtorrent issue, or Windscribe's. I'll address the issue at Windscribe, too. Sorry for the incomplete info!

ltGuillaume on 23 Apr 2018

No worries 😄 Better to report than not.

vktr on 23 Apr 2018

Alright, I just got word on https://www.reddit.com/r/Windscribe/comments/8edz8d/qbittorrentpicotorrent_100_cpu_when_reconnecting/ that an issue for qBittorrent has opened since the creation of this issue, https://github.com/qbittorrent/qBittorrent/issues/8740.

The erratic behavior is seen as soon as Windscribe terminates the socket by force in order to prevent any leaking while not connected to the VPN server.

This could either be addressed in the @libtorrent library, as hinted by 2 users in the issue, or a workaround could be implemented in the client (checking for existence of socket and aborting the endless connection retries which cause the CPU use).

ltGuillaume on 23 Apr 2018

👍1

Thanks for the investigation! 😄

vktr on 26 Apr 2018

Windscribe dev here. You can also reproduce the issue by terminating the TCP socket with https://www.nirsoft.net/utils/cports.html to take the VPN out of the equation.

This issue seems to affect a wide range of software that doesn't handle unexpected socket termination. This includes Plex, qBittorrent, Acronis True Image, Avid Media Manager.