Subversion svn+ssh, sshd 100% CPU

Question

In the past few days I have been doing extensive testing of Subversion with different clients, operating systems, client and server versions and have noticed very strange behaviour with windows clients connecting to Linux servers, hitting them with excessive CPU usage on the sshd process, where the Linux clients do not exhibit this behaviour.

A sample test setup is as follows: Server Linux Ubuntu 16.04.3 LTS, OpenSSH_7.2p2 Ubuntu-4ubuntu2.2, OpenSSL 1.0.2g 1 Mar 2016, Subversion version 1.9.3 (and 1.9.7). Client TortoiseSVN 1.9.7

When checking out large repositories the linux server is hit on the sshd process, the process running with 100% cpu usage. This in effect slows down the performance and ultimately the speed at which the checkout runs. Linux clients connecting to the same server do not cause this load on the server.

This happens even when compressions is turned off and when encryption Cyphers are changed, as well as different versions of subversion. The behaviour is identical. I'm not sure who to address for this issue as this not only happens with TortoiseSVN but with SlikSVN as well. Any direction would be appreciated.

Answer 1

If you're just looking for a way for a controlled set of users to access your SVN servers, an easy workaround for any Windows 10 users is to have them use SVN from WSL (Windows Subsystem for Linux). In fact, I would consider testing that route to isolate the client from the network stack, etc.

It's worth noting that default SVN settings may be to convert line endings, and the SVN server may be converting every file, every line to Windows default line endings.

Likely better answers out there, but those are my initial thoughts.