VisualSVN Server 3.9 Release Notes

VisualSVN Server 3.9 has the following main enhancements:

Update to the latest Apache Subversion 1.10 release.
A number of significant performance improvements.

For the complete list of changes, see the VisualSVN Server 3.9.0 changelog.

Upgrade to VisualSVN Server 3.9 is recommended for all users. The upgrade is easy and straightforward, but existing Subversion repositories require format upgrade to fully benefit from upgrading to VisualSVN Server 3.9.

For further details, we strongly advise reading the KB138: Upgrading to VisualSVN Server 3.9 article beforehand (especially if you are upgrading from versions older than VisualSVN Server 3.0).

The users of multisite Subversion repositories based on VisualSVN Distributed File System (VDFS) should follow a special upgrade procedure. Read the article KB139: Upgrading to VisualSVN Server 3.9 in a multisite environment for further details.

Upgrade to Apache Subversion 1.10

Apache Subversion 1.10 is a major Apache Software Foundation release that provides the following improvements:

LZ4 compression. Subversion 1.10 introduces support for LZ4 compression that can provide a noticeable performance boost — especially when working with large binary files. Subversion automatically compresses data in repositories and on the wire using LZ4 algorithm when both server and client use Subversion 1.10. Existing Subversion repositories require a format upgrade to allow using LZ4 compression.
Interactive tree-conflict resolver. The new conflict resolver offers a variety of automated tree conflict resolution options which users can choose from. When tree conflicts cannot be resolved automatically, Subversion 1.10 offers an interactive resolver and provides a detailed tree conflict information including revision numbers and names of authors of conflicting changes. Using the new tree conflict resolver requires an upgraded Subversion 1.10 client.

For the complete list of notable improvements, please consider Apache Subversion 1.10 Release Notes. Note that VisualSVN Server uses its own dedicated module for authorization and the improvements made to path-based authorization in Subversion 1.10 were not included into VisualSVN Server 3.9.

Many performance enhancements

In addition to the performance improvements implemented in Subversion 1.10, VisualSVN Server provides extra performance improvements:

Significantly reduced CPU usage for HTTP compression during common operations.
Improved performance over WAN on Windows Server 2012 and later.
Improved commit performance into slave VDFS repositories.

Cumulatively with the core SVN 1.10 changes, these improvements provide a 50-100% performance boost that is most noticeable for commit operations.

Upgrade and compatibility concerns

Upgrade to VisualSVN Server 3.9 is recommended for all users. Read the KB138: Upgrading to VisualSVN Server 3.9 article before upgrading. The upgrade is free for Standard Edition users and all customers who have an active maintenance subscription for VisualSVN Server Enterprise Edition licenses.

VisualSVN Server 3.9 is built with Apache Subversion 1.10 and is backward compatible with older Subversion clients. Older Subversion clients interoperate transparently with VisualSVN Server 3.9. However, some of the new Subversion 1.10 features may not be available unless both client and server are at the latest versions:

LZ4 compression on the wire is available only for Subversion 1.10 clients.
The new interactive tree-conflict resolver is available only for Subversion 1.10 clients.
For best results with the new tree conflict resolver, all Subversion clients committing to the repository should be at version 1.8 or higher.