Question

I want to simplify this:

<target name="build">
   <parallel>
      <antcall target="build-A" />
      <antcall target="build-B" />
      <antcall target="build-C" />
   </parallel>
</target>

<target name="build-A">
   <exec executable="tool.exe" dir="projects/A">
      <arg value="input.xml" />
   </exec>
</target>

where build-B and build-C do the exact same thing (only in dirs B and C, respectively), into something akin to this:

<dirset id="projects" dir="." >
   <include name="projects/*" />
</dirset>

<apply executable="tool.exe" parallel="true">
   <arg value="input.xml" />
   <dirset refid="projects" />
</apply>

This doesn’t work because apply will do one of the following:

If parallel is set to true,

tool.exe input.xml projects/A projects/B projects/C

or if parallel is set to false,

tool.exe projects/A/input.xml
...waits for tool.exe to complete...
tool.exe projects/B/input.xml
...etc

And even that is incorrect because tool.exe expects to be run within the projects/A directory.

Is there a way to parallelize this such that the output I get is equivalent to:

cd project/A
tool.exe input.xml

cd ../B
tool.exe input.xml

cd ../C
tool.exe input.xml

but in parallel?

Answer 1

I’d use ant-contrib‘s for task to do this.

<for param="dir" parallel="true">
    <dirset id="projects" dir="." >
        <include name="projects/*" />
    </dirset>
    <sequential>
        <exec executable="tool.exe" dir="@{dir}">
            <arg value="input.xml" />
        </exec>
    </sequential>
</for>