macOS stand-alone client fails

With PR #11 initializing a Server object and connecting a client to this server works. However, when trying to build the Client as standalone, an exception is raised. Strangely, the path should be added (see client.py) and the file libiomp5.dylib is in the folder.

Exception                                 Traceback (most recent call last)
/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/_jpype.cpython-37m-darwin.so in com.comsol.model.util.ModelUtil.initStandalone()

/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/_jpype.cpython-37m-darwin.so in com.comsol.model.util.ServerModelUtil.initStandalone()

/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/_jpype.cpython-37m-darwin.so in com.comsol.model.util.ServerModelUtil.initStandalone()

/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/_jpype.cpython-37m-darwin.so in java.security.AccessController.doPrivileged()

/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/_jpype.cpython-37m-darwin.so in com.comsol.model.util.ServerModelUtil$17.run()

/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/_jpype.cpython-37m-darwin.so in java.lang.System.load()

/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/_jpype.cpython-37m-darwin.so in java.lang.Runtime.load0()

/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/_jpype.cpython-37m-darwin.so in java.lang.ClassLoader.loadLibrary()

/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/_jpype.cpython-37m-darwin.so in java.lang.ClassLoader.loadLibrary0()

/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/_jpype.cpython-37m-darwin.so in java.lang.ClassLoader$NativeLibrary.load()

Exception: Java Exception

The above exception was the direct cause of the following exception:

java.lang.UnsatisfiedLinkError            Traceback (most recent call last)
<ipython-input-3-23d2b50bf9f8> in <module>
----> 1 c = mph.Client()

/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/mph/client.py in __init__(self, cores, version, port, host)
    147             logger.info('Initializing stand-alone client.')
    148             graphics = True
--> 149             java.initStandalone(graphics)
    150             logger.info('Stand-alone client initialized.')
    151         # Otherwise skip stand-alone initialization and connect to server.

java.lang.UnsatisfiedLinkError: java.lang.UnsatisfiedLinkError: /Applications/COMSOL55/Multiphysics/lib/maci64/libcssystemutil.dylib: dlopen(/Applications/COMSOL55/Multiphysics/lib/maci64/libcssystemutil.dylib, 1): Library not loaded: @rpath/libiomp5.dylib
  Referenced from: /Applications/COMSOL55/Multiphysics/lib/maci64/libcssystemutil.dylib
  Reason: image not found

[shomikverma]

I may have found solution to this - setting DYLD_FALLBACK_LIBRARY_PATH instead of DYLD_LIBRARY_PATH. As discussed here, macos only checks in the fallback path if the library isn’t found in the default path. This ensures nothing breaks when adding the COMSOL paths necessary. Setting:

export DYLD_FALLBACK_LIBRARY_PATH=/Applications/COMSOL56/Multiphysics/lib/maci64:/Applications/COMSOL56/Multiphysics/ext/graphicsmagick/maci64:/Applications/COMSOL56/Multiphysics/ext/cadimport/maci64

allows me to do:

In [1]: import mph

In [2]: import matplotlib.pyplot as plt

In [3]: mph.option('session','stand-alone')

In [4]: client = mph.start(1)

with no issues! I also had to change line 481 in client.py to DYLD_FALLBACK_LIBRARY_PATH instead of DYLD_LIBRARY_PATH so the script would check the right environment variable.

[john-hen]

Thanks for looking into this and reporting back. Good to know, I was not aware of that. This may help people who want to use stand-alone mode on macOS, but run into compatibility problems with other graphics libraries.

Strange though that there seems to be no Linux equivalent, like LD_FALLBACK_LIBRARY_PATH. At least a cursory web search did not turn up anything.

I’ll fix the checks of the environment variables in the next release. They are not necessary anyway, but certainly shouldn’t get in the way of doing things right.