Embedding, "import site", PYTHONHOME, and an old, old issue

Discussion in 'Python' started by Jim Hill, Feb 10, 2007.

  1. Jim Hill

    Jim Hill Guest

    Well, I've found about a hundred thousand web pages where people have
    had the same problem I have but nary a page with a solution that works
    for me.

    I want to do a simple embed, so I've followed the example in the
    Extending and Embedding documentation:

    In the .c file,

    #include <Python.h>

    int routine() {
    Py_Initialize();
    PyRun_SimpleString("from time import time,ctime\n"
    "print 'Today is',ctime(time())\n");
    Py_Finalize();
    return 0;
    }

    The code compiles just fine, but when I execute it the call to
    Py_Initialize() comes back with:

    'import site' failed; use -v for traceback
    Traceback (most recent call last):
    File "<string>", line 1, in <module>
    ImportError: No module named time



    I found a lot of websites that say to set PYTHONHOME to the the path to
    the directory where site.py lives. I did that but I get the same error.

    Here are a few bits o' additional information:

    'python -v' tells me it was built with gcc 3.4.4 (and has no trouble at
    all finding site.py whether PYTHONHOME is defined or not). The
    following code snippet:

    >>> import distutils.sysconfig
    >>> distutils.sysconfig.get_config_var('LINKFORSHARED')


    comes back with '-Xlinker -export-dynamic'.

    My own code needs to use Portland Group's pgi. I did some googling for
    various permutations of nouns from the preceding few paragraphs and
    found Pythonic mention of using "-Wl,-export-dynamic" as a flag for the
    PG linker. OK, try that, builds fine, same error.

    I cannot recompile Python on this machine and I don't really understand
    exactly what is happening with the Py_* function calls in the C snippet
    above, or whether I can get more detailed traceback info. This is the
    first time I've tried embedding and it's rather obvious that I've run
    into a problem that everyone but Messrs. van Rossum and Lundh has hit.
    Somebody, somewhere must have an honest-to-glub solution. If you are
    that somebody, please let me know what to do because I'm about to throw
    in the towel and embed That Other Language.

    Oh, one more thing: if I launch python from the shell and type in the
    strings from the C snippet it works fine.

    Thanks,


    Jim
    --

    It's not "pretexting", it's "lying."
    Jim Hill, Feb 10, 2007
    #1
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  2. Jim Hill

    Jim Hill Guest

    Jim Hill (that'd be me) wrote:

    I forgot one more key thing: the compiled code is being run via mpirun
    (LAM/MPI). Might that have something to do with my pain and heartache?


    Jim

    (original post reproduced below in shocking breach of etiquette on the
    off chance someone's interested in this post and didn't bother reading
    the first.)


    >Well, I've found about a hundred thousand web pages where people have
    >had the same problem I have but nary a page with a solution that works
    >for me.
    >
    >I want to do a simple embed, so I've followed the example in the
    >Extending and Embedding documentation:
    >
    >In the .c file,
    >
    >#include <Python.h>
    >
    >int routine() {
    > Py_Initialize();
    > PyRun_SimpleString("from time import time,ctime\n"
    > "print 'Today is',ctime(time())\n");
    > Py_Finalize();
    > return 0;
    > }
    >
    >The code compiles just fine, but when I execute it the call to
    >Py_Initialize() comes back with:
    >
    >'import site' failed; use -v for traceback
    >Traceback (most recent call last):
    > File "<string>", line 1, in <module>
    >ImportError: No module named time
    >
    >
    >
    >I found a lot of websites that say to set PYTHONHOME to the the path to
    >the directory where site.py lives. I did that but I get the same error.
    >
    >Here are a few bits o' additional information:
    >
    >'python -v' tells me it was built with gcc 3.4.4 (and has no trouble at
    >all finding site.py whether PYTHONHOME is defined or not). The
    >following code snippet:
    >
    > >>> import distutils.sysconfig
    > >>> distutils.sysconfig.get_config_var('LINKFORSHARED')

    >
    >comes back with '-Xlinker -export-dynamic'.
    >
    >My own code needs to use Portland Group's pgi. I did some googling for
    >various permutations of nouns from the preceding few paragraphs and
    >found Pythonic mention of using "-Wl,-export-dynamic" as a flag for the
    >PG linker. OK, try that, builds fine, same error.
    >
    >I cannot recompile Python on this machine and I don't really understand
    >exactly what is happening with the Py_* function calls in the C snippet
    >above, or whether I can get more detailed traceback info. This is the
    >first time I've tried embedding and it's rather obvious that I've run
    >into a problem that everyone but Messrs. van Rossum and Lundh has hit.
    >Somebody, somewhere must have an honest-to-glub solution. If you are
    >that somebody, please let me know what to do because I'm about to throw
    >in the towel and embed That Other Language.
    >
    >Oh, one more thing: if I launch python from the shell and type in the
    >strings from the C snippet it works fine.

    --

    It's not "pretexting", it's "lying."
    Jim Hill, Feb 10, 2007
    #2
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  3. En Sat, 10 Feb 2007 03:57:05 -0300, Jim Hill <> escribió:

    > I want to do a simple embed, so I've followed the example in the
    > Extending and Embedding documentation:
    >
    > In the .c file,
    >
    > #include <Python.h>
    >
    > int routine() {
    > Py_Initialize();
    > PyRun_SimpleString("from time import time,ctime\n"
    > "print 'Today is',ctime(time())\n");
    > Py_Finalize();
    > return 0;
    > }


    (Why routine() and not main()? Unfortunately you can't repeteadly
    initialize/finalize the interpreter, you must do that only once.)

    > The code compiles just fine, but when I execute it the call to
    > Py_Initialize() comes back with:
    >
    > 'import site' failed; use -v for traceback
    > Traceback (most recent call last):
    > File "<string>", line 1, in <module>
    > ImportError: No module named time


    Try this:
    PyRun_SimpleString("import sys; print sys.path");
    to see where Python expects to find its library (or call the Py_GetPath
    function).

    You may need to call Py_SetProgramName (before Py_Initialize) so it can
    find where the standard library resides.
    At least for testing purposes, you can copy your executable into the same
    directory where Python is installed.

    --
    Gabriel Genellina
    Gabriel Genellina, Feb 10, 2007
    #3
  4. Jim Hill

    Jim Hill Guest

    Gabriel Genellina wrote:
    >En Sat, 10 Feb 2007 03:57:05 -0300, Jim Hill <> escribió:
    >
    >> int routine() {
    >> Py_Initialize();
    >> ...
    >> }

    >
    >(Why routine() and not main()? Unfortunately you can't repeteadly
    >initialize/finalize the interpreter, you must do that only once.)


    This is a small routine tucked off to the side of a fairly large
    mostly-FORTRAN-with-some-C program. I need to parse a slash-delimited
    input file from a different program and fill up some arrays with the
    results. Rather than wrestle with FORTRAN's wretched file I/O I thought
    I'd do it this way.

    >Try this:
    >PyRun_SimpleString("import sys; print sys.path");
    >to see where Python expects to find its library (or call the Py_GetPath
    >function).


    It returned a list of paths nearly identical to what the interactive
    interpreter does -- it's on a different machine and too long to retype
    here -- the interactive sys.path has an empty string as item 0, while
    the embedded sys.path returns the interactive[1:n].

    >You may need to call Py_SetProgramName (before Py_Initialize) so it can
    >find where the standard library resides.


    Didn't do anything, alas.

    >At least for testing purposes, you can copy your executable into the same
    >directory where Python is installed.


    No can do -- it's not my machine and I don't have appropriate
    privileges. Thanks for trying to help me out but I'm on a crash
    deadline and it looks like I'll be doing some C parsing. Blech.


    Jim
    --

    It's not "pretexting", it's "lying."
    Jim Hill, Feb 12, 2007
    #4
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