如何获取Ant中的availableProcessors数量

Question

我想从我的Ant构建脚本获取availableProcessors的数量（即从Runtime.getRuntime（）。availableProcessors（）返回的值。是否存在包含此值的现有属性，或者我是否必须编写自定义ant任务？

Answer 1

This post by Ilia Chemodanov explains two solutions nicely.

If you don't want to compile and import a Java class you can do it in pure ant: (though it is pretty hacky)

<target name="get-cores">
    <property environment="env"/>
    <!-- support for Windows -->
    <condition property="cores.count" value="${env.NUMBER_OF_PROCESSORS}">
        <os family="windows" />
    </condition>
    <!-- support for Linux and Solaris (package SUNWgnu-coreutils is required) -->
    <exec executable="nproc" outputproperty="cores.count" os="Linux,SunOS,Solaris">
        <arg value="--all"/>
    </exec>
    <!-- support for Mac OS X -->
    <exec executable="sysctl" outputproperty="cores.count" os="Mac OS X">
        <arg value="-n"/>
        <arg value="hw.ncpu"/>
    </exec>
    <echo message="Number of cores: ${cores.count}"/>
</target>

Answer 2

编写自定义ant任务 ，就像写一个类一样简单

Answer 3

The JVM does not provide such a property and neither does ant. Instead of writing a custom task you could do one of the following:

1. Write a Java class that prints the number of processors to standard output. Use the java task with the outputproperty attribute to set the value to a property for use in ant.
2. If you are only ever building one a single platform use the exec task to call something native that prints the number of processors to standard output. As above use the outputproperty attribute to set the value to a property for use in ant.

Answer 4

Like @dfa mentioned, writing your own custom task it's a good option.

However, if the host that builds your service is different from the host running it, then the number of cores will differ (you will get the number of available processors of the host that build your service).

If you DON'T want that, then you can just use a small shell script inside your build script, something like this (for UNIX like OSs):

$(/usr/bin/nproc --all)

I'd check if the command exists first, if(type /usr/bin/nproc) .... but that depends on how you want to implement it.

Answer 5

I never heard about such a property, thus I think you should write your custom task.

Manu