python: PYTHONHOME may not be the same as the prefix of the python ex…#2173
python: PYTHONHOME may not be the same as the prefix of the python ex…#2173tgamblin merged 1 commit intospack:developfrom BarrySmith:barry/fix-pythonhome
Conversation
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@BarrySmith: I don't think this is quite right either. This gets the Also was Spack using Two questions:
I am not sure that (2) works in all cases. In particular, looking at how Homebrew installs Python I'm not sure what we can assume about Whereas the Python prefix in the Cellar is much more extensive. I am curious what would happen if you tried to |
Users don't read documentation, simple things should just work
I will update the pull request with your second suggestion (I checked that it works (with a few fixes)) in a few minutes. Any python code that needs to know about the python directory and uses the properly sys.exec or sys.exec_prefix works fine with the brew python install (even without all the directories in /usr/local) it is only tools that incorrectly think the python executable has to be carefully located in the big python directory tree that don't work properly :-) Note that the Apply python does this same thing of having most of the directory tree off in some other directory. But why are you even setting PYTHONHOME? Any properly installed Python should not need PYTHONHOME. Just don't set it and my problem goes away without complicated fixes. |
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I believe we set it because |
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@BarrySmith: flake8 |
Fixed |
| extension and any other python extensions it depends on.""" | ||
| pythonhome = self.prefix | ||
| spack_env.set('PYTHONHOME', pythonhome) | ||
| python = Executable(os.path.join(self.prefix, 'python')) |
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This will break for Python3. We need to find another way...
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In setup_dependent_package(), we use syntax like:
'python{0}'.format('3' if self.spec.satisfies('@3') else '')This could easily be used here too. I wonder if we can make it a more generic property.
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This PR makes me uneasy because, whatever problem it solves, the fix will not work for |
Good point. The PR could check for the existence of python or python3 at that location and if only one of the two exists then use it; but that doesn't help if there are both files there. Note that in my packages.yaml file I have That is I don't indicate if the binary should be python or python3; is there a way for me to indicate that (based on the path how do you pick which one to use?)? And if I could list the executable then this information must be stored somewhere so couldn't it get pulled out of where it is stored and used here to select the correct binary? |
IMHO you do by specifying version |
Oh right, so I could possibly set python vs python3 based on the version information. Is python3 used for python version 3+ on all systems or do you have in spack someway a routine to map from version number to python3 based on the system (you must if you can determine the version to use from the python@version in the packages file)? Thanks |
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I am not a python user, but i think the code above by @adamjstewart choose python3 for version 3 and above, and python otherwise. I would try that first. |
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If you download Various system installations fiddle with this convention. MacOS Python is If you know you're looking at a Spack-installed Python, then you can assume If you're looking at any old random Python installation, you will have to I would not assume you're looking at a Spack-installed Python: users could On Sun, Oct 30, 2016 at 1:01 PM, Denis Davydov [email protected]
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…ecutable On MacOS, brew installs /usr/local/bin/python but the Python prefix is not /usr/local/bin Use the python command sys.exec to get the correct directory, instead of the ad hoc self.prefix previously used This was a bear to debug; been driving me nuts since I started using spack. Since spack passes PYTHONHOME down to package builds in the environment it was passing PYTHONHOME of /usr/local/bin to the PETSc build that uses Python so the PETSc Python ./configure errored immediately with ImportError: No module named site since python could find no python modules. Todd Gamblin pointed out that my first try to fix this was wrong since it assumed the spack python was the same python used to run spack. Elizabeth Fischer suggested how to get it to work also with python3 Funded-by: IDEAS Project: IDEAS/xSDK Time: 7 hours Thanks-to: Todd Gamblin, Elizabeth Fischer
@citibeth Updated to resolve the python3 issue |
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Thanks! On Sun, Oct 30, 2016 at 6:12 PM, Barry Smith [email protected]
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@citibeth can you approve the changes so I don't have to dismiss your review? |
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Oh sorry, I didn't realize that requesting changes on the new GitHub review feature came with responsibilities... |
…ython executable (spack#2173)" This is to avoid issue reported here: spack#2208 This reverts commit a714377.
## Motivation Python installations are both important and unfortunately inconsistent. Depending on the Python version, OS, and the strength of the Earth's magnetic field when it was installed, the name of the Python executable, directory containing its libraries, library names, and the directory containing its headers can vary drastically. I originally got into this mess with #3274, where I discovered that Boost could not be built with Python 3 because the executable is called `python3` and we were telling it to use `python`. I got deeper into this mess when I started hacking on #3140, where I discovered just how difficult it is to find the location and name of the Python libraries and headers. Currently, half of the packages that depend on Python and need to know this information jump through hoops to determine the correct information. The other half are hard-coded to use `python`, `spec['python'].prefix.lib`, and `spec['python'].prefix.include`. Obviously, none of these packages would work for Python 3, and there's no reason to duplicate the effort. The Python package itself should contain all of the information necessary to use it properly. This is in line with the recent work by @alalazo and @davydden with respect to `spec['blas'].libs` and friends. ## Prefix For most packages in Spack, we assume that the installation directory is `spec['python'].prefix`. This generally works for anything installed with Spack, but gets complicated when we include external packages. Python is a commonly used external package (it needs to be installed just to run Spack). If it was installed with Homebrew, `which python` would return `/usr/local/bin/python`, and most users would erroneously assume that `/usr/local` is the installation directory. If you peruse through #2173, you'll immediately see why this is not the case. Homebrew actually installs Python in `/usr/local/Cellar/python/2.7.12_2` and symlinks the executable to `/usr/local/bin/python`. `PYTHONHOME` (and presumably most things that need to know where Python is installed) needs to be set to the actual installation directory, not `/usr/local`. Normally I would say, "sounds like user error, make sure to use the real installation directory in your `packages.yaml`". But I think we can make a special case for Python. That's what we decided in #2173 anyway. If we change our minds, I would be more than happy to simplify things. To solve this problem, I created a `spec['python'].home` attribute that works the same way as `spec['python'].prefix` but queries Python to figure out where it was actually installed. @tgamblin Is there any way to overwrite `spec['python'].prefix`? I think it's currently immutable. ## Command In general, Python 2 comes with both `python` and `python2` commands, while Python 3 only comes with a `python3` command. But this is up to the OS developers. For example, `/usr/bin/python` on Gentoo is actually Python 3. Worse yet, if someone is using an externally installed Python, all 3 commands may exist in the same directory! Here's what I'm thinking: If the spec is for Python 3, try searching for the `python3` command. If the spec is for Python 2, try searching for the `python2` command. If neither are found, try searching for the `python` command. ## Libraries Spack installs Python libraries in `spec['python'].prefix.lib`. Except on openSUSE 13, where it installs to `spec['python'].prefix.lib64` (see #2295 and #2253). On my CentOS 6 machine, the Python libraries are installed in `/usr/lib64`. Both need to work. The libraries themselves change name depending on OS and Python version. For Python 2.7 on macOS, I'm seeing: ``` lib/libpython2.7.dylib ``` For Python 3.6 on CentOS 6, I'm seeing: ``` lib/libpython3.so lib/libpython3.6m.so.1.0 lib/libpython3.6m.so -> lib/libpython3.6m.so.1.0 ``` Notice the `m` after the version number. Yeah, that's a thing. ## Headers In Python 2.7, I'm seeing: ``` include/python2.7/pyconfig.h ``` In Python 3.6, I'm seeing: ``` include/python3.6m/pyconfig.h ``` It looks like all Python 3 installations have this `m`. Tested with Python 3.2 and 3.6 on macOS and CentOS 6 Spack has really nice support for libraries (`find_libraries` and `LibraryList`), but nothing for headers. Fixed.
## Motivation Python installations are both important and unfortunately inconsistent. Depending on the Python version, OS, and the strength of the Earth's magnetic field when it was installed, the name of the Python executable, directory containing its libraries, library names, and the directory containing its headers can vary drastically. I originally got into this mess with spack#3274, where I discovered that Boost could not be built with Python 3 because the executable is called `python3` and we were telling it to use `python`. I got deeper into this mess when I started hacking on spack#3140, where I discovered just how difficult it is to find the location and name of the Python libraries and headers. Currently, half of the packages that depend on Python and need to know this information jump through hoops to determine the correct information. The other half are hard-coded to use `python`, `spec['python'].prefix.lib`, and `spec['python'].prefix.include`. Obviously, none of these packages would work for Python 3, and there's no reason to duplicate the effort. The Python package itself should contain all of the information necessary to use it properly. This is in line with the recent work by @alalazo and @davydden with respect to `spec['blas'].libs` and friends. ## Prefix For most packages in Spack, we assume that the installation directory is `spec['python'].prefix`. This generally works for anything installed with Spack, but gets complicated when we include external packages. Python is a commonly used external package (it needs to be installed just to run Spack). If it was installed with Homebrew, `which python` would return `/usr/local/bin/python`, and most users would erroneously assume that `/usr/local` is the installation directory. If you peruse through spack#2173, you'll immediately see why this is not the case. Homebrew actually installs Python in `/usr/local/Cellar/python/2.7.12_2` and symlinks the executable to `/usr/local/bin/python`. `PYTHONHOME` (and presumably most things that need to know where Python is installed) needs to be set to the actual installation directory, not `/usr/local`. Normally I would say, "sounds like user error, make sure to use the real installation directory in your `packages.yaml`". But I think we can make a special case for Python. That's what we decided in spack#2173 anyway. If we change our minds, I would be more than happy to simplify things. To solve this problem, I created a `spec['python'].home` attribute that works the same way as `spec['python'].prefix` but queries Python to figure out where it was actually installed. @tgamblin Is there any way to overwrite `spec['python'].prefix`? I think it's currently immutable. ## Command In general, Python 2 comes with both `python` and `python2` commands, while Python 3 only comes with a `python3` command. But this is up to the OS developers. For example, `/usr/bin/python` on Gentoo is actually Python 3. Worse yet, if someone is using an externally installed Python, all 3 commands may exist in the same directory! Here's what I'm thinking: If the spec is for Python 3, try searching for the `python3` command. If the spec is for Python 2, try searching for the `python2` command. If neither are found, try searching for the `python` command. ## Libraries Spack installs Python libraries in `spec['python'].prefix.lib`. Except on openSUSE 13, where it installs to `spec['python'].prefix.lib64` (see spack#2295 and spack#2253). On my CentOS 6 machine, the Python libraries are installed in `/usr/lib64`. Both need to work. The libraries themselves change name depending on OS and Python version. For Python 2.7 on macOS, I'm seeing: ``` lib/libpython2.7.dylib ``` For Python 3.6 on CentOS 6, I'm seeing: ``` lib/libpython3.so lib/libpython3.6m.so.1.0 lib/libpython3.6m.so -> lib/libpython3.6m.so.1.0 ``` Notice the `m` after the version number. Yeah, that's a thing. ## Headers In Python 2.7, I'm seeing: ``` include/python2.7/pyconfig.h ``` In Python 3.6, I'm seeing: ``` include/python3.6m/pyconfig.h ``` It looks like all Python 3 installations have this `m`. Tested with Python 3.2 and 3.6 on macOS and CentOS 6 Spack has really nice support for libraries (`find_libraries` and `LibraryList`), but nothing for headers. Fixed.
## Motivation Python installations are both important and unfortunately inconsistent. Depending on the Python version, OS, and the strength of the Earth's magnetic field when it was installed, the name of the Python executable, directory containing its libraries, library names, and the directory containing its headers can vary drastically. I originally got into this mess with spack#3274, where I discovered that Boost could not be built with Python 3 because the executable is called `python3` and we were telling it to use `python`. I got deeper into this mess when I started hacking on spack#3140, where I discovered just how difficult it is to find the location and name of the Python libraries and headers. Currently, half of the packages that depend on Python and need to know this information jump through hoops to determine the correct information. The other half are hard-coded to use `python`, `spec['python'].prefix.lib`, and `spec['python'].prefix.include`. Obviously, none of these packages would work for Python 3, and there's no reason to duplicate the effort. The Python package itself should contain all of the information necessary to use it properly. This is in line with the recent work by @alalazo and @davydden with respect to `spec['blas'].libs` and friends. ## Prefix For most packages in Spack, we assume that the installation directory is `spec['python'].prefix`. This generally works for anything installed with Spack, but gets complicated when we include external packages. Python is a commonly used external package (it needs to be installed just to run Spack). If it was installed with Homebrew, `which python` would return `/usr/local/bin/python`, and most users would erroneously assume that `/usr/local` is the installation directory. If you peruse through spack#2173, you'll immediately see why this is not the case. Homebrew actually installs Python in `/usr/local/Cellar/python/2.7.12_2` and symlinks the executable to `/usr/local/bin/python`. `PYTHONHOME` (and presumably most things that need to know where Python is installed) needs to be set to the actual installation directory, not `/usr/local`. Normally I would say, "sounds like user error, make sure to use the real installation directory in your `packages.yaml`". But I think we can make a special case for Python. That's what we decided in spack#2173 anyway. If we change our minds, I would be more than happy to simplify things. To solve this problem, I created a `spec['python'].home` attribute that works the same way as `spec['python'].prefix` but queries Python to figure out where it was actually installed. @tgamblin Is there any way to overwrite `spec['python'].prefix`? I think it's currently immutable. ## Command In general, Python 2 comes with both `python` and `python2` commands, while Python 3 only comes with a `python3` command. But this is up to the OS developers. For example, `/usr/bin/python` on Gentoo is actually Python 3. Worse yet, if someone is using an externally installed Python, all 3 commands may exist in the same directory! Here's what I'm thinking: If the spec is for Python 3, try searching for the `python3` command. If the spec is for Python 2, try searching for the `python2` command. If neither are found, try searching for the `python` command. ## Libraries Spack installs Python libraries in `spec['python'].prefix.lib`. Except on openSUSE 13, where it installs to `spec['python'].prefix.lib64` (see spack#2295 and spack#2253). On my CentOS 6 machine, the Python libraries are installed in `/usr/lib64`. Both need to work. The libraries themselves change name depending on OS and Python version. For Python 2.7 on macOS, I'm seeing: ``` lib/libpython2.7.dylib ``` For Python 3.6 on CentOS 6, I'm seeing: ``` lib/libpython3.so lib/libpython3.6m.so.1.0 lib/libpython3.6m.so -> lib/libpython3.6m.so.1.0 ``` Notice the `m` after the version number. Yeah, that's a thing. ## Headers In Python 2.7, I'm seeing: ``` include/python2.7/pyconfig.h ``` In Python 3.6, I'm seeing: ``` include/python3.6m/pyconfig.h ``` It looks like all Python 3 installations have this `m`. Tested with Python 3.2 and 3.6 on macOS and CentOS 6 Spack has really nice support for libraries (`find_libraries` and `LibraryList`), but nothing for headers. Fixed.
## Motivation Python installations are both important and unfortunately inconsistent. Depending on the Python version, OS, and the strength of the Earth's magnetic field when it was installed, the name of the Python executable, directory containing its libraries, library names, and the directory containing its headers can vary drastically. I originally got into this mess with spack#3274, where I discovered that Boost could not be built with Python 3 because the executable is called `python3` and we were telling it to use `python`. I got deeper into this mess when I started hacking on spack#3140, where I discovered just how difficult it is to find the location and name of the Python libraries and headers. Currently, half of the packages that depend on Python and need to know this information jump through hoops to determine the correct information. The other half are hard-coded to use `python`, `spec['python'].prefix.lib`, and `spec['python'].prefix.include`. Obviously, none of these packages would work for Python 3, and there's no reason to duplicate the effort. The Python package itself should contain all of the information necessary to use it properly. This is in line with the recent work by @alalazo and @davydden with respect to `spec['blas'].libs` and friends. ## Prefix For most packages in Spack, we assume that the installation directory is `spec['python'].prefix`. This generally works for anything installed with Spack, but gets complicated when we include external packages. Python is a commonly used external package (it needs to be installed just to run Spack). If it was installed with Homebrew, `which python` would return `/usr/local/bin/python`, and most users would erroneously assume that `/usr/local` is the installation directory. If you peruse through spack#2173, you'll immediately see why this is not the case. Homebrew actually installs Python in `/usr/local/Cellar/python/2.7.12_2` and symlinks the executable to `/usr/local/bin/python`. `PYTHONHOME` (and presumably most things that need to know where Python is installed) needs to be set to the actual installation directory, not `/usr/local`. Normally I would say, "sounds like user error, make sure to use the real installation directory in your `packages.yaml`". But I think we can make a special case for Python. That's what we decided in spack#2173 anyway. If we change our minds, I would be more than happy to simplify things. To solve this problem, I created a `spec['python'].home` attribute that works the same way as `spec['python'].prefix` but queries Python to figure out where it was actually installed. @tgamblin Is there any way to overwrite `spec['python'].prefix`? I think it's currently immutable. ## Command In general, Python 2 comes with both `python` and `python2` commands, while Python 3 only comes with a `python3` command. But this is up to the OS developers. For example, `/usr/bin/python` on Gentoo is actually Python 3. Worse yet, if someone is using an externally installed Python, all 3 commands may exist in the same directory! Here's what I'm thinking: If the spec is for Python 3, try searching for the `python3` command. If the spec is for Python 2, try searching for the `python2` command. If neither are found, try searching for the `python` command. ## Libraries Spack installs Python libraries in `spec['python'].prefix.lib`. Except on openSUSE 13, where it installs to `spec['python'].prefix.lib64` (see spack#2295 and spack#2253). On my CentOS 6 machine, the Python libraries are installed in `/usr/lib64`. Both need to work. The libraries themselves change name depending on OS and Python version. For Python 2.7 on macOS, I'm seeing: ``` lib/libpython2.7.dylib ``` For Python 3.6 on CentOS 6, I'm seeing: ``` lib/libpython3.so lib/libpython3.6m.so.1.0 lib/libpython3.6m.so -> lib/libpython3.6m.so.1.0 ``` Notice the `m` after the version number. Yeah, that's a thing. ## Headers In Python 2.7, I'm seeing: ``` include/python2.7/pyconfig.h ``` In Python 3.6, I'm seeing: ``` include/python3.6m/pyconfig.h ``` It looks like all Python 3 installations have this `m`. Tested with Python 3.2 and 3.6 on macOS and CentOS 6 Spack has really nice support for libraries (`find_libraries` and `LibraryList`), but nothing for headers. Fixed.
5 participants
…ecutable
On MacOS, brew installs /usr/local/bin/python but the Python prefix is not /usr/local/bin
Use the python command sys.exec to get the correct directory, instead of the ad hoc self.prefix
previously used
This was a bear to debug; been driving me nuts since I started using spack.
Since spack passes PYTHONHOME down to package builds in the environment
it was passing PYTHONHOME of /usr/local/bin to the PETSc build that uses Python so
the PETSc Python ./configure errored immediately with
ImportError: No module named site
since python could find no python modules
Funded-by: IDEAS
Project: IDEAS/xSDK
Time: 6 hours