[pylucene-dev] finding the JVM DLL on Windows...

[Andi Vajda]

On Fri, 25 Apr 2008, Bill Janssen wrote:

> I'd like to reopen an issue we talked about earlier.
>
> I'm having difficulties running PyLucene 2.4.0 (JCC 1.9, shared) on
> Windows XP.  I've put the "jcc.dll" file into the
> PYTHON/Lib/site-packages/lucene/ directory, which seems to work, but
> it's complaining that "The application has failed to start because
> jvm.dll was not found."
>
> I think that this is going to be a persistent problem on Windows.
> Even though I have the Java "bin" directory on my path, the jvm.dll is
> in "bin/client", and so is not found.
>
> What I'd like to do is to have the following prologue inserted into
> the lucene/__init__.py file.  It adds the registry's current location
> for jvm.dll to the end of the Path environment variable.  This means
> that a location explicitly specified by the user will override this
> default value, but it also means that a location for the dll will
> always be found, and reduce what I expect to be one of the most
> troublesome errors using JCC PyLucene on Windows.

Yes, you have shown that this is possible before. I've also said before that 
I'm a little unsure about putting this stuff in for everyone as I'm very 
suspicious of registry-based hacks. What works for your setup may not work 
for everyone else's setup. Others may then have very strange errors because 
there is some 'well hidden' kludge in an __init__.py file messing with 
people's PATH.

To me, messing with people's PATHs behind their backs very much sounds like 
a no-no. Alarm bells go off. If it works for your setup, though, I don't see 
any problem with you having this code in a piece of python that runs 
_before_ the lucene module is imported. And it would appear to solve the 
problem for your setup very well then.

Or am I missing something ?

Are there any actual Windows users (I'm not) on this list (besides Bill) 
who have an opinion about this ?

Andi..

>
> Bill
> ---------------------------------------------------------------
>
> import sys
> if sys.platform == 'win32':
>
>    # figure out where the jvm.dll is, and make sure that location is on sys.path
>    import _winreg as wreg
>    registry = wreg.ConnectRegistry(None, wreg.HKEY_LOCAL_MACHINE)
>    key = wreg.OpenKey(registry, r"SOFTWARE\JavaSoft\Java Runtime Environment")
>    v, t = wreg.QueryValueEx(key, "CurrentVersion")
>    key = wreg.OpenKey(registry, r"SOFTWARE\JavaSoft\Java Runtime Environment\%s" % v)
>    javahome, t = wreg.QueryValueEx(key, "JavaHome")
>    registry.Close()
>    # if we have a javahome, make sure it's on the list
>    if javahome:
>        import os
>        location = os.path.join(javahome, "bin", "client")
>        os.environ['Path'] = os.pathsep.join(os.environ['Path'].split(os.pathsep) + [location,])
>
>
>
>
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