On Sun, Jul 14, 2013 at 1:12 PM, Noah Kantrowitz <n...@coderanger.net> wrote: > > On Jul 14, 2013, at 9:45 AM, Steve Dower wrote: > >> From: Paul Moore >>> On 13 July 2013 10:05, Paul Moore <p.f.mo...@gmail.com> wrote: >>> How robust is the process of upgrading pip using itself? Specifically on >>> Windows, where these things typically seem less reliable. >>> >>> OK, I just did some tests. On Windows, "pip install -U pip" FAILS. The >>> reason >>> for the failure is simple enough to explain - the pip.exe wrapper is held >>> open >>> by the OS while it's in use, so that the upgrade cannot replace it. >>> >>> The result is a failed upgrade and a partially installed new version of >>> pip. In >>> practice, the exe stubs are probably added fairly late in the install (at >>> least >>> when installing from sdist, with a wheel that depends on the order of the >>> files >>> in the wheel), so it's probably only a little bit broken, but "a little bit >>> broken" is still broken :-( >>> >>> On the other hand, "python -m pip install -U pip" works fine because it >>> avoids >>> the exe wrappers. >>> >>> There's a lot of scope for user confusion and frustration in all this. For >>> standalone pip I've tended to recommend "don't do that" - manually >>> uninstall and >>> reinstall pip, or recreate your virtualenv. It's not nice, but it's >>> effective. >>> That sort of advice isn't going to be realistic for a pip bundled with >>> CPython. >>> >>> Does anyone have any suggestions? >> >> Unless I misunderstand how the exe wrappers work (they're all the same code >> that looks for a .py file by the same name?) it may be easiest to somehow >> mark them as non-vital, such that failing to update them does not fail the >> installer. Maybe detect that it can't be overwritten, compare the >> contents/hash with the new one, and only fail if it's changed (with an >> instruction to use 'python -m...')? >> >> Spawning a separate process to do the install is probably no good, since >> you'd have to kill the original one which is going to break command line >> output. >> >> MoveFileEx (with its copy-on-reboot flag) is off the table, since it >> requires elevation and a reboot. But I think that's the only supported API >> for doing a deferred copy. >> >> If Windows was opening .exes with FILE_SHARE_DELETE then it would be >> possible to delete the exe and create a new one by the same name, but I >> doubt that will work and in any case could not be assumed to never change. >> >> So unless the exe wrapper is changing with each version, I think the best >> way of handling this is to not force them to be replaced when they have not >> changed. > > The usual way to do this is just move the existing executable to > pip.exe.deleteme or something, and then write out the new one. Then on every > startup (or maybe some level of special case for just pip upgrades?) try to > unlink *.deleteme. Not the simplest system ever, but it gets the job done.
I accidentally only emailed Paul earlier, but why can't we upgrade the pip module with the exe and then replace the process (using something in the os.exec* family) with `python -m pip update-exe` which could then succeed since the OS isn't holding onto the exe file? I could be missing something entirely obvious since I haven't developed (directly) on or for Windows in at least 5 years. _______________________________________________ Distutils-SIG maillist - Distutils-SIG@python.org http://mail.python.org/mailman/listinfo/distutils-sig
