Python distutils在不同的机器上以不同方式构建扩展

时间:2010-06-30 01:34:45

标签: python build dependencies distutils

我一直在研究包含大量文件的Python扩展模块。在一台机器上构建时,python setup.py build将很高兴地检测到已更改的文件,只构建这些文件,并将整个事物链接在一起,就像make一样。但是,在另一台机器上,对任何文件的单个更改会触发重新编译所有源。

要清楚。两台机器都会检测包装是否是最新的,不会做任何事情。只有当单个文件发生变化时,它们的行为才会发生变化。

为什么第二台机器会这样做?

计算机1(进行适当的每文件依赖性检查和构建。)

Python 2.6.4 (r264:75706, Feb 15 2010, 17:06:03) 
[GCC 4.1.2 20080704 (Red Hat 4.1.2-44)] on linux2
Type "help", "copyright", "credits" or "license" for more information.

setuptools-0.6c11-py2.6

LSB Version: :core-3.1-amd64:core-3.1-ia32:core-3.1-noarch:graphics-3.1-amd64:graphics-3.1-ia32:graphics-3.1-noarch
Distributor ID: CentOS
Description: CentOS release 5.4 (Final)
Release: 5.4
Codename: Final

机器2(当单个源文件发生变化时重建所有内容。)

Python 2.6.5 (r265:79063, Apr 16 2010, 13:57:41) 
[GCC 4.4.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.

setuptools-0.6c11-py2.6

No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 10.04 LTS
Release: 10.04
Codename: lucid

2 个答案:

答案 0 :(得分:2)

我查看了Mercurial回购并发现了这一变化:

Issue #5372:在Distutils的ccompiler中删除.o文件的重用(因为扩展额外选项可能会更改输出而不更改.c文件)。

IOW,这是一个简单的优化,已被删除。

答案 1 :(得分:1)

我已经跟踪了Python 2.6.4和Python 2.6.5之间的distutils的变化。 distutils.ccompiler.CCompiler中的两种方法,即_setup_compile_prep_compile,删除了相同的代码块:

if self.force:
    skip_source = {}            # rebuild everything
    for source in sources:
        skip_source[source] = 0
elif depends is None:
    # If depends is None, figure out which source files we
    # have to recompile according to a simplistic check. We
    # just compare the source and object file, no deep
    # dependency checking involving header files.
    skip_source = {}            # rebuild everything
    for source in sources:      # no wait, rebuild nothing
        skip_source[source] = 1

    n_sources, n_objects = newer_pairwise(sources, objects)
    for source in n_sources:    # no really, only rebuild what's
        skip_source[source] = 0 # out-of-date
else:
    # If depends is a list of files, then do a different
    # simplistic check.  Assume that each object depends on
    # its source and all files in the depends list.
    skip_source = {}
    # L contains all the depends plus a spot at the end for a
    # particular source file
    L = depends[:] + [None]
    for i in range(len(objects)):
        source = sources[i]
        L[-1] = source
        if newer_group(L, objects[i]):
            skip_source[source] = 0
        else:
            skip_source[source] = 1

此代码根据目标对象检查每个源文件,如果它早于目标,则将其标记为跳过。我不知道为什么它被删除了,但它解释了这种差异。当我把它作为测试重新放入时,编译器将恢复为每源依赖性分析。