Versions of .NET

Release 2.4.0

  • Released on 2009-03-13

Release notes


Mono 2.4 is a portable and open source implementation of the .NET framework for Unix, Windows, MacOS and other operating systems.

Table of contents

Major Highlights

This is a release focused on stability and performance and it is also the foundation for Novell's own long-term support Mono-based product.

Changes since Mono 2.2

This documents the changes since Mono 2.2.


SIMD support in Mono

SIMD constructors are now optimized. A few APIs have been renamed to better suit the Design Guidelines.

No more polling

One of the most challenging components of Mono was supporting Thread.Interrupt in a way that worked across multiple operating systems. In previous versions of Mono, the only solution we found that was portable was to poll every 100ms for potential interruptions requested by another thread.

Starting with Mono 2.4, that polling code is no longer present and instead a cross-platform solution to the problem is being used that provides both support for Thread.Interrupt() and does not consume CPU cycles.

Other Changes

  • The old JIT has been removed, and only the new linear IR based JIT is available.
  • The --enable-parallel-mark=yes argument to configure is now the default, this speeds up garbage collections on multi-core machines.
  • WaitHandle now supports SignalAndWait.
  • MarshalByRefObject supports MemberwiseClone
  • COM: support NULLs IDispatch and IUnknown.

Behavioral Changes

Our System.Diagnostics.Process implementation will now properly raise the termination event on OutputDataReceived and ErrorDataReceived. See bug 459450 for details.


Support for Real Time Signals, it is now possible to fetch the list of real-time signals in a cross-platform way.


Optimized the XPath code which reduces memory consumption in our own tests by 15%.

DateTime.TryParse does no longer depend on internal try/catches.

Loading resources from a satellite assembly does not internally throw exceptions.


Precompiled Web Sites

Mono's ASP.NET stack can now run precompiled ASP.NET web sites generated with Visual Studio or using the aspnet_compiler. This allows Mono to support ASP.NET applications written in languages other than C# or applications that take advantage of new VB.NET features not available on Mono's VB compiler.

Typically web sites are compiled like this from the command line:

c:\test\>aspnet_compiler -f -p c:\test\BlogEngine.Web -v /blog c:\test\output

Alternatively, this can be done with Visual Studio using the "Publish" feature.

Performance: Single Domain Support

If only one application is configured in mod_mono or Mono's XSP Mono will eliminate the intermediate multiplexor/demultiplexor for requests and instead send and receive the data straight from one domain to the kernel.

This eliminates a number of calls into Mono's Remoting stack that is required when multiple applications are running.


Many improvements to the DataGridView control to better support DataBinding.

Installing Mono 2.4

Binary Packages and Source Code Downloads:

Source code and pre-compiled packages for Linux, Solaris,
MacOS X and Windows is available from our web site from
the Downloads section.

Quick source code installation:

If we have no packages for your platform, installing from
source code is very simple.

Compile libgdiplus to support System.Drawing:

    $ tar xzf libgdiplus-2.4.tar.gz
    $ cd libgdiplus-2.4
    $ ./configure
    $ make
    $ make install

Then compile Mono itself:

    $ tar xzf mono-2.4.tar.gz
    $ cd mono-2.4
    $ ./configure
    $ make
    $ make install