nix-gh/doc/manual/release-notes/rl-0.16.xml

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<section xmlns="http://docbook.org/ns/docbook"
xmlns:xlink="http://www.w3.org/1999/xlink"
xmlns:xi="http://www.w3.org/2001/XInclude"
version="5.0"
xml:id="ssec-relnotes-0.16">
<title>Release 0.16 (2010-08-17)</title>
<para>This release has the following improvements:</para>
<itemizedlist>
<listitem>
<para>The Nix expression evaluator is now much faster in most
cases: typically, <link
xlink:href="http://www.mail-archive.com/nix-dev@cs.uu.nl/msg04113.html">3
to 8 times compared to the old implementation</link>. It also
uses less memory. It no longer depends on the ATerm
library.</para>
</listitem>
<listitem>
<para>
Support for configurable parallelism inside builders. Build
scripts have always had the ability to perform multiple build
actions in parallel (for instance, by running <command>make -j
2</command>), but this was not desirable because the number of
actions to be performed in parallel was not configurable. Nix
now has an option <option>--cores
<replaceable>N</replaceable></option> as well as a configuration
setting <varname>build-cores =
<replaceable>N</replaceable></varname> that causes the
environment variable <envar>NIX_BUILD_CORES</envar> to be set to
<replaceable>N</replaceable> when the builder is invoked. The
builder can use this at its discretion to perform a parallel
build, e.g., by calling <command>make -j
<replaceable>N</replaceable></command>. In Nixpkgs, this can be
enabled on a per-package basis by setting the derivation
attribute <varname>enableParallelBuilding</varname> to
<literal>true</literal>.
</para>
</listitem>
<listitem>
<para><command>nix-store -q</command> now supports XML output
through the <option>--xml</option> flag.</para>
</listitem>
<listitem>
<para>Several bug fixes.</para>
</listitem>
</itemizedlist>
</section>