McSinyx
/
pip
mirror of https://github.com/pypa/pip
1
1
Fork 0
Code Issues Releases Activity

Update the wheel-cache-disabling docs with our latest understanding of C compiler nondeterminism.

This commit is contained in:
Erik Rose 2015-10-21 16:35:30 -04:00
parent f38fc903f2
commit 4488047ef6
1 changed files with 7 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
docs/reference/pip_install.rst
View File

@ -516,10 +516,13 @@ those wheels would be selected for installation, but their hashes would not
match the sdist ones from the requirements file. A further complication is that
locally built wheels are nondeterministic: contemporary modification times make
their way into the archive, making hashes unpredictable across machines and
cache flushes. However, wheels fetched from index servers land in pip's HTTP
cache, not its wheel cache, and are used normally in hash-checking mode. The
only potential penalty is thus extra build time for sdists, and this can be
solved by making sure pre-built wheels are available from the index server.
cache flushes. Compilation of C code adds further nondeterminism, as many
compilers include random-seeded values in their output. However, wheels fetched
from index servers are the same every time. They land in pip's HTTP cache, not
its wheel cache, and are used normally in hash-checking mode. The only downside
of having the the wheel cache disabled is thus extra build time for sdists, and
this can be solved by making sure pre-built wheels are available from the index
server.
Hash-checking mode also works with :ref:`pip download` and :ref:`pip wheel`. A
:ref:`comparison of hash-checking mode with other repeatability strategies