Vray 7.00.10 Hython error

[john_morch]

Hi there, I'm trying to create some vrscene files using hython. The process is as follows, I have a python script that takes a Houdini scene file and a rop node path and just calls the "render" function of the rop node.
I call that python script with hython executable and pass in my arguments. However, when I run hython I get the following error. The script continues executing but there is no vrscene generation.
One other odd thing I noted is that when I print the node type of the vray rop node, it's output as a "merge" node, I'm assuming this is why nothing gets generated. I have confirmed that the rop node is vray_renderer.
When I export and render interactively from the houdini UI everything works as expected. Also running vray standalone on a interactively generated vrscene works as well.

Here is a summary of system/versions.

OS: Linux Rocky 9.3
Houdini: 20.5.487
V-Ray for Houdini hash:6cf69be from 28 Jan 2025 16:36
V-Ray Core 7.00.10 [125d49e9] from 23 Jan 2025

Traceback from Unhandled Exception Loading /array/X/Library/renderer/vray/70010/houdini/houdini20.5.487/vfh_home/dso_py311/20.5.487/vray_for_houdini.so: <unknown exception type>
utCallFunc(char const*, void (*)(void*), void*) [clone .cold] <libHoudiniUT.so>
UT_DSO::run(char const*, void*, bool) <libHoudiniUT.so>
OP_OperatorTable::runDSOInstall() <libHoudiniPRM.so>
OP_Network::getOperatorTable(UT_StringRef const&, char const*) <libHoudiniPRM.so>
MGR_Node::buildRopTable(char const*) <libHoudiniOPZ.so>
MOT_Director::MOT_Director(UT_StringHolder const&, bool, bool, bool) <libHoudiniOPZ.so>
HOMF_Module::createHoudiniInternals() <libHoudiniOPZ.so>
_wrap___createHoudiniInternals <_hou.so>
cfunction_vectorcall_NOARGS <libpython3.11.so.1.0>
PyObject_Vectorcall.localalias <libpython3.11.so.1.0>
_PyEval_EvalFrameDefault.localalias <libpython3.11.so.1.0>
_PyEval_Vector <libpython3.11.so.1.0>
PyEval_EvalCode.localalias <libpython3.11.so.1.0>
builtin_exec <libpython3.11.so.1.0>
cfunction_vectorcall_FASTCALL_KEYWORDS <libpython3.11.so.1.0>
_PyEval_EvalFrameDefault.localalias <libpython3.11.so.1.0>
_PyFunction_Vectorcall.localalias <libpython3.11.so.1.0>
object_vacall <libpython3.11.so.1.0>
PyObject_CallMethodObjArgs.localalias <libpython3.11.so.1.0>
PyImport_ImportModuleLevelObject.localalias <libpython3.11.so.1.0>
_PyEval_EvalFrameDefault.localalias <libpython3.11.so.1.0>
_PyEval_Vector <libpython3.11.so.1.0>
PyEval_EvalCode.localalias <libpython3.11.so.1.0>
run_eval_code_obj <libpython3.11.so.1.0>
run_mod <libpython3.11.so.1.0>
PyRun_StringFlags.localalias (pythonrun.c:1601)
PyRun_SimpleStringFlags.localalias <libpython3.11.so.1.0>
pyInitializePython(bool) <libHoudiniUT.so>
PYmakeSurePythonIsInitialized(bool) <libHoudiniUT.so>
PY_BaseInterpreterAutoLock::PY_BaseInterpreterAutoLock(bool) <libHoudiniUT.so>
[0x40c44e] <hython-bin>
[0x40ad67] <hython-bin>
__libc_start_call_main <libc.so.6>
__libc_start_main_alias_2 <libc.so.6>
[0x40ad9c] <hython-bin>

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[Gosho.Genchev]

Hey john_morch ,

I'd wager V-Ray is not loaded when you're calling Hython.
1) Are you using the package system or setting up the environment variables yourself?
2) Are you doing "source houdini_setup" from $HFS prior to calling Hython?

Our automated tests use the same approach - calling hython to work with pre-prepared HIP files. Our Linux tests are passing so it must be something with the environment on your end.
I suppose you could try "import os; print(os.environ())" in the hython process to check if the V-Ray related variables are present at all.
If you don't see them - a random guess I have is that maybe you've installed V-Ray for the shared 20.5 symlink folder under /opt/ and the vray_for_houdini.json file that loads the V-Ray data is present under the packages folder there --> but you're instead calling hython from the folder of the specific 20.5.487 version.

Best regards!

[Gosho.Genchev]

edit:

I just realized I've missed the first line in the traceback - this error I've seen when I've ended up loading a plugin more than once - I recall it happening when I've got the JSON file present in multiple locations - could you please try looking into the /documents/houdini20.5/packages folder, the shared /opt/hfs20.5/packages folder, and the /opt/hfs20.5.487/packages folder to make sure the vray_for_houdini.json file is only present in only one of these locations?

best regards!

[john_morch]

Gosho.Genchev Thanks for the suggestions.

1. I'm using rez to create the Houdini and Vray for Houdini environments. I'm not using the vray_for_houdini.json. But, I actually did try using that file, https://docs.chaos.com/display/VRAYH...ation+from+zip, and added an entry for 20.5.487 and removing my rez environment for vray for houdini to see if that would fix the issue, but I ran into the same problem.
2. I am not sourcing houdini_setup. It wasn't an issue with vray 6.20.23 running hython and generating vrscene files. Perhaps worth a shot.
3. I checked the folders mentioned and there is no vray_for_houdini.json located there.

Here is the environment for vray from the hython process.

('VRAY_OSL_PATH', '/array/X/Library/renderer/vray/70010/houdini/houdini20.5.487/appsdk/bin')
('VRAY_UI_DS_PATH', '/array/X/Library/renderer/vray/70010/houdini/houdini20.5.487/ui')
('VRAY_FOR_HOUDINI_APPSDK_BIN', '/array/X/Library/renderer/vray/70010/houdini/houdini20.5.487/appsdk/bin')
('VFH_ASSET_PATH', '[MTLLIB_DOWNLOAD_DIR]/assets')
('VRAY_SDK', '/array/X/Library/renderer/vray/70010/houdini/houdini20.5.487/appsdk')
('VRAY_APPSDK', '/array/X/Library/renderer/vray/70010/houdini/houdini20.5.487/appsdk')
('VFH_DSO_PATH', '/array/X/Library/renderer/vray/70010/houdini/houdini20.5.487/vfh_home/dso_py311/20.5.487')
('VRAY_AUTH_CLIENT_FILE_PATH', '/array/X/Library/licenses/Chaos2/vray/lic-01')
('VFH_HOME', '/array/X/Library/renderer/vray/70010/houdini/houdini20.5.487/vfh_home')
('HOUDINI_DSO_PATH', '/array/X/Library/renderer/vray/70010/houdini/houdini20.5.487/vfh_home/dso_py311/20.5.487:&')
('VRAY_UI_DS_VRAY61', '1')
('HOUDINI_PATH', '/opt/hfs20.5.487/packages/sculpt:/opt/hfs20.5.487/packages/kinefx:/opt/hfs20.5.487/packages/apex_cop:/opt/hfs20.5.487/packages/apex:/home/loneill/packages/dm_houdini_core/1.0.2/python/deadline:/home/loneill/packages/dm_houdini_core/1.0.2/menu:/home/loneill/packages/dm_houdini_core/1.0.2:/array/X/Library/renderer/vray/70010/houdini/houdini20.5.487/vfh_home:&')

This setup works fine for 6.20.23 and houdini 19.5.605. The only addition, environment wise for 7.00.10, is VRAY_FOR_HOUDINI_APPSDK_BIN.
I'll try narrowing down the rez dependencies and see if I can get any more information that way.
Let me know if there is anything else that I can try. Thanks.

[john_morch]

Gosho.Genchev

Some updates.

1. I tried 6.20.25 with Houdini 20.5.487 and that works, vrscenes are generated as expected, and the standalone render works and renders as expected.
2. I tried the minimal rez environment, just houdini and vray for houdini and that gave the same error.