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?
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
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
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
和_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skip_source[source] = 0 # out-of-date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。