Hey
as soon there is a Arnold Shader or Rop present in the hip file PDG Processes stop working due a loading redundancy on Arnold side.
Ive been told by SideFx Support:
"Work items in the ROP Fetch node run out of process, as child processes of the main Houdini session, which means they inherit the environment from the parent session. Arnold tries to detect itself in the environment and skips loading nodes if it's already found in the environment, which is what happens in the child process that's cooking the ROP. That only causes issues if there are actually Arnold nodes in the scene, which then break on loading the .hip."

Ive been able to work around that by Unsetting the Houdini Path Variable in the TOP Scheduler.
But not anymore. I understand that its not directly an Arnold Error but its cause by it.

here is a log from the process:

00:00:00 373MB | log started Mon Jan 3 08:54:07 2022

00:00:00 373MB | Arnold 7.0.0.1 [5e3b4fd3] linux clang-10.0.1 oiio-2.3.2 osl-1.12.0 vdb-7.1.1 clm-2.0.0.235 rlm-14.1.3 optix-6.6.0 2021/11/18 12:38:35

00:00:00 373MB | running on WORK00, pid=9446

00:00:00 373MB | 1 x AMD Ryzen Threadripper PRO 3995WX 64-Cores (64 cores, 128 logical) with 128697MB

00:00:00 373MB | NVIDIA driver version 470.86 (Optix 60801)

00:00:00 373MB | GPU 0: NVIDIA TITAN RTX @ 1770MHz (compute 7.5) with 24217MB (22918MB available) (NVLink:0)

00:00:00 373MB | GPU 1: NVIDIA GeForce RTX 2080 Ti @ 1635MHz (compute 7.5) with 11019MB (11010MB available) (NVLink:0)

00:00:00 373MB | Linux Mint 19.3 (Tricia), Linux kernel 5.4.0-91-generic

00:00:00 373MB | soft limit for open files is set at 4094

00:00:00 373MB |

00:00:00 373MB | [metadata] loading metadata file: /opt/htoa/htoa-6.0.2.0_r0ad447a_houdini-19.0.455.py3/htoa-6.0.2.0_r0ad447a_houdini-19.0.455.py3/dso/../scripts/bin/arnold.mtd

00:00:00 391MB | [color_manager_ocio] default ocio.config found in /opt/htoa/htoa-6.0.2.0_r0ad447a_houdini-19.0.455.py3/htoa-6.0.2.0_r0ad447a_houdini-19.0.455.py3/dso/../scripts/bin/../ocio/configs/arnold/config.ocio

00:00:00 391MB | loading plugins from /opt/htoa/htoa-6.0.2.0_r0ad447a_houdini-19.0.455.py3/htoa-6.0.2.0_r0ad447a_houdini-19.0.455.py3/dso/../scripts/bin/../plugins ...

00:00:00 391MB | cryptomatte.so: cryptomatte uses Arnold 7.0.0.1

00:00:00 391MB | cryptomatte.so: cryptomatte_filter uses Arnold 7.0.0.1

00:00:00 391MB | cryptomatte.so: cryptomatte_manifest_driver uses Arnold 7.0.0.1

00:00:00 391MB | [metadata] loading metadata file: /opt/htoa/htoa-6.0.2.0_r0ad447a_houdini-19.0.455.py3/htoa-6.0.2.0_r0ad447a_houdini-19.0.455.py3/dso/../scripts/bin/../plugins/cryptomatte.mtd

00:00:00 391MB | htoa_mandelbulb_proc.so: mandelbulb uses Arnold 7.0.0.1

00:00:00 391MB | [metadata] loading metadata file: /opt/htoa/htoa-6.0.2.0_r0ad447a_houdini-19.0.455.py3/htoa-6.0.2.0_r0ad447a_houdini-19.0.455.py3/dso/../scripts/bin/../plugins/htoa_mandelbulb_proc.mtd

00:00:00 400MB | usd_proc.so: usd uses Arnold 7.0.0.1

00:00:00 400MB | [metadata] loading metadata file: /opt/htoa/htoa-6.0.2.0_r0ad447a_houdini-19.0.455.py3/htoa-6.0.2.0_r0ad447a_houdini-19.0.455.py3/dso/../scripts/bin/../plugins/usd_proc.mtd

00:00:00 400MB | alembic_proc.so: alembic uses Arnold 7.0.0.1

00:00:00 400MB | [metadata] loading metadata file: /opt/htoa/htoa-6.0.2.0_r0ad447a_houdini-19.0.455.py3/htoa-6.0.2.0_r0ad447a_houdini-19.0.455.py3/dso/../scripts/bin/../plugins/alembic_proc.mtd

00:00:00 400MB | loaded 6 plugins from 4 lib(s) in 0:00.01

00:00:00 436MB | [htoa_op] Begin registration ...

00:00:00 436MB | [obj_procedurals] Registering procedurals ...

00:00:00 436MB | [obj_procedurals] procedural registration done.

00:00:00 436MB | [obj_procedurals] Registering procedurals ...

00:00:00 436MB | [obj_procedurals] procedural registration done.

00:00:00 452MB | [rop_operators] Registering operators ...

00:00:00 452MB | [rop_operators] operator registration done.

00:00:00 452MB | [htoa_op] End registration.

00:00:00 452MB |

00:00:00 452MB | releasing resources

00:00:00 453MB | unloading 4 plugins

00:00:00 453MB | closing cryptomatte.so ...

00:00:00 453MB | closing htoa_mandelbulb_proc.so ...

00:00:00 453MB | closing usd_proc.so ...

00:00:00 453MB | closing alembic_proc.so ...

00:00:00 452MB | unloading plugins done

00:00:00 452MB | Arnold shutdown

00:00:00 452MB | [rop_operators] Registering operators ...

00:00:00 452MB | [rop_operators] operator registration done.

00:00:00 485MB | [vop_shaders] Registering shaders ...

00:00:00 485MB | [vop_shaders] shader registration done.

00:00:00 485MB | [vop_imagers] Registering imagers ...

00:00:00 485MB | [vop_imagers] imager registration done.

00:00:00 485MB | [vop_shaders] Registering shaders ...

00:00:00 485MB | [vop_shaders] shader registration done.

00:00:00 485MB | [vop_imagers] Registering imagers ...

00:00:00 485MB | [vop_imagers] imager registration done.

libai.so already loaded

[htoa] HTOA environment variable already set to /opt/htoa/htoa-6.0.2.0_r0ad447a_houdini-19.0.455.py3/htoa-6.0.2.0_r0ad447a_houdini-19.0.455.py3

00:00:00 564MB | log started Mon Jan 3 08:54:09 2022

00:00:00 564MB | Arnold 7.0.0.1 [5e3b4fd3] linux clang-10.0.1 oiio-2.3.2 osl-1.12.0 vdb-7.1.1 clm-2.0.0.235 rlm-14.1.3 optix-6.6.0 2021/11/18 12:38:35

00:00:00 564MB | running on WORK00, pid=9446

00:00:00 564MB | 1 x AMD Ryzen Threadripper PRO 3995WX 64-Cores (64 cores, 128 logical) with 128697MB

00:00:00 564MB | NVIDIA driver version 470.86 (Optix 60801)

00:00:00 564MB | GPU 0: NVIDIA TITAN RTX @ 1770MHz (compute 7.5) with 24217MB (22918MB available) (NVLink:0)

00:00:00 564MB | GPU 1: NVIDIA GeForce RTX 2080 Ti @ 1635MHz (compute 7.5) with 11019MB (11010MB available) (NVLink:0)

00:00:00 564MB | Linux Mint 19.3 (Tricia), Linux kernel 5.4.0-91-generic

00:00:00 564MB | soft limit for open files is set at 4094

00:00:00 564MB |

00:00:00 564MB | [metadata] loading metadata file: /opt/htoa/htoa-6.0.2.0_r0ad447a_houdini-19.0.455.py3/htoa-6.0.2.0_r0ad447a_houdini-19.0.455.py3/dso/../scripts/bin/arnold.mtd

00:00:00 565MB | [color_manager_ocio] default ocio.config found in /opt/htoa/htoa-6.0.2.0_r0ad447a_houdini-19.0.455.py3/htoa-6.0.2.0_r0ad447a_houdini-19.0.455.py3/dso/../scripts/bin/../ocio/configs/arnold/config.ocio

00:00:00 565MB | loading plugins from /opt/htoa/htoa-6.0.2.0_r0ad447a_houdini-19.0.455.py3/htoa-6.0.2.0_r0ad447a_houdini-19.0.455.py3/dso/../scripts/bin/../plugins ...

00:00:00 565MB | cryptomatte.so: cryptomatte uses Arnold 7.0.0.1

00:00:00 565MB | cryptomatte.so: cryptomatte_filter uses Arnold 7.0.0.1

00:00:00 565MB | cryptomatte.so: cryptomatte_manifest_driver uses Arnold 7.0.0.1

00:00:00 565MB | htoa_mandelbulb_proc.so: mandelbulb uses Arnold 7.0.0.1

00:00:00 565MB | usd_proc.so: usd uses Arnold 7.0.0.1

00:00:00 565MB | alembic_proc.so: alembic uses Arnold 7.0.0.1

00:00:00 565MB | loaded 6 plugins from 4 lib(s) in 0:00.00

00:00:00 565MB | unloading 4 plugins

00:00:00 565MB | closing cryptomatte.so ...

00:00:00 565MB | closing htoa_mandelbulb_proc.so ...

00:00:00 565MB | closing usd_proc.so ...

00:00:00 565MB | closing alembic_proc.so ...

00:00:00 565MB | unloading plugins done

00:00:00 565MB | Arnold shutdown

00:00:00 565MB | log started Mon Jan 3 08:54:09 2022

00:00:00 565MB | Arnold 7.0.0.1 [5e3b4fd3] linux clang-10.0.1 oiio-2.3.2 osl-1.12.0 vdb-7.1.1 clm-2.0.0.235 rlm-14.1.3 optix-6.6.0 2021/11/18 12:38:35

00:00:00 565MB | running on WORK00, pid=9446

00:00:00 565MB | 1 x AMD Ryzen Threadripper PRO 3995WX 64-Cores (64 cores, 128 logical) with 128697MB

00:00:00 565MB | NVIDIA driver version 470.86 (Optix 60801)

00:00:00 565MB | GPU 0: NVIDIA TITAN RTX @ 1770MHz (compute 7.5) with 24217MB (22918MB available) (NVLink:0)

00:00:00 565MB | GPU 1: NVIDIA GeForce RTX 2080 Ti @ 1635MHz (compute 7.5) with 11019MB (11010MB available) (NVLink:0)

00:00:00 565MB | Linux Mint 19.3 (Tricia), Linux kernel 5.4.0-91-generic

00:00:00 565MB | soft limit for open files is set at 4094

00:00:00 565MB |

00:00:00 565MB | [metadata] loading metadata file: /opt/htoa/htoa-6.0.2.0_r0ad447a_houdini-19.0.455.py3/htoa-6.0.2.0_r0ad447a_houdini-19.0.455.py3/dso/../scripts/bin/arnold.mtd

00:00:00 581MB | unloading 4 plugins

00:00:00 581MB | closing cryptomatte.so ...

00:00:00 581MB | closing htoa_mandelbulb_proc.so ...

00:00:00 581MB | closing usd_proc.so ...

00:00:00 581MB | closing alembic_proc.so ...

00:00:00 581MB | unloading plugins done

00:00:00 581MB | Arnold shutdown

[htoa] HTOA environment variable already set to /opt/htoa/htoa-6.0.2.0_r0ad447a_houdini-19.0.455.py3/htoa-6.0.2.0_r0ad447a_houdini-19.0.455.py3

[08:54:09.747] Running Houdini 19.0.455 with PID 9446

[08:54:09.747] Loading .hip file /mnt/jobs/XXXXXXXXXXXXXXXXXXX/D_BUILD/rnd_bb_a03.hip.

[08:54:10.608] Traceback (most recent call last):

File "/tmp/houdini_temp/rnd_bb_a03/pdgtemp/4087/scripts/rop.py", line 1724, in <module>

main()

File "/tmp/houdini_temp/rnd_bb_a03/pdgtemp/4087/scripts/rop.py", line 1720, in main

run_job(settings)

File "/tmp/houdini_temp/rnd_bb_a03/pdgtemp/4087/scripts/rop.py", line 1477, in run_job

raise e

File "/tmp/houdini_temp/rnd_bb_a03/pdgtemp/4087/scripts/rop.py", line 1471, in run_job

hou.hipFile.load(hip_local, ignore_load_warnings=True)

File "/opt/hfs19.0/houdini/python3.7libs/hou.py", line 50501, in load

return _hou.hipFile_load(self, file_name, suppress_save_prompt, ignore_load_warnings)

hou.OperationFailed: The attempted operation failed.

Error loading: /mnt/jobs/XXXXXXXXXXXXXXXXXXX/D_BUILD/rnd_bb_a03.hip

Warning: Bad node type found: arnold::standard_surface in /obj/matnet1/GLASS.

Error: Unknown operator on load "standard_surface1.def".

Unknown operator on load "standard_surface1.parm".

Unknown operator on load "standard_surface1.userdata".

Warning: Bad node type found: arnold::standard_surface in /obj/matnet1/WATER.

Error: Unknown operator on load "standard_surface1.def".

Unknown operator on load "standard_surface1.parm".

Unknown operator on load "standard_surface1.userdata".

Warning: Bad node type found: arnold::standard_surface in /obj/matnet1/AIR.

Error: Unknown operator on load "standard_surface1.def".

Unknown operator on load "standard_surface1.parm".

Unknown operator on load "standard_surface1.userdata".

Warning: Bad node type found: arnold::standard_surface in /obj/matnet1/DIFF.

Error: Unknown operator on load "standard_surface1.def".

Unknown operator on load "standard_surface1.parm".

Unknown operator on load "standard_surface1.userdata".