**Error**:
```bash=
~/dev/torchcodec (main*) » python test/decoders/manual_smoke_test.py nicolashug@nicolashug-fedora-PF372ZT9
Traceback (most recent call last):
File "/home/nicolashug/dev/torchcodec/test/decoders/manual_smoke_test.py", line 4, in <module>
import torchcodec
File "/home/nicolashug/dev/torchcodec/src/torchcodec/__init__.py", line 1, in <module>
from . import decoders, samplers # noqa
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/nicolashug/dev/torchcodec/src/torchcodec/samplers/__init__.py", line 5, in <module>
from .video_clip_sampler import * # noqa
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/nicolashug/dev/torchcodec/src/torchcodec/samplers/video_clip_sampler.py", line 12, in <module>
from torchcodec.decoders._core import (
File "/home/nicolashug/dev/torchcodec/src/torchcodec/decoders/_core/__init__.py", line 5, in <module>
from .video_decoder_ops import * # noqa
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/nicolashug/dev/torchcodec/src/torchcodec/decoders/_core/video_decoder_ops.py", line 10, in <module>
torch.ops.load_library(_get_extension_path("libtorchcodec"))
File "/home/nicolashug/.miniconda3/envs/codec/lib/python3.11/site-packages/torch/_ops.py", line 1278, in load_library
ctypes.CDLL(path)
File "/home/nicolashug/.miniconda3/envs/codec/lib/python3.11/ctypes/__init__.py", line 376, in __init__
self._handle = _dlopen(self._name, mode)
^^^^^^^^^^^^^^^^^^^^^^^^^
OSError: /home/nicolashug/.miniconda3/envs/codec/bin/../lib/libstdc++.so.6: version `GLIBCXX_3.4.32' not found (required by /home/nicolashug/dev/torchcodec/src/torchcodec/libtorchcodec.so)
```
**Problem**: I compiled and linked torchcodec against `/usr/lib64/libstdc++.so.6` but at runtime the one that gets loaded is `/home/nicolashug/.miniconda3/envs/codec/bin/../lib/libstdc++.so.6`, and it's missing some version symbols.
**IT IS NOT PYTHON'S FAULT IT IS OPENCV!!!!!!!!!!!!!**
First: `torchcodec` WORKS:
```
~/dev/torchcodec (main*) » LD_DEBUG=libs python -c "import torchcodec" 2>&1 | grep libstd 130 ↵ nicolashug@nicolashug-fedora-PF372ZT9
133672: find library=libstdc++.so.6 [0]; searching
133672: trying file=/home/nicolashug/.miniconda3/envs/codec/lib/python3.11/site-packages/torch/lib/libstdc++.so.6
133672: trying file=/lib64/libstdc++.so.6
133672: calling init: /lib64/libstdc++.so.6
133672: calling fini: /lib64/libstdc++.so.6 [0]
```
There's no error here, I can import `torchcodec` without and error and ``/usr/lib64/libstdc++.so.6`` gets properly loaded.
So it's not Python who is loading the wrong `/home/nicolashug/.miniconda3/envs/codec/bin/../lib/libstdc++.so.6` (well... we'll see).
The loading of the wrong `/home/nicolashug/.miniconda3/envs/codec/bin/../lib/libstdc++.so.6` comes from opencv:
```
~/dev/torchcodec (main*) » LD_DEBUG=libs python -c "import cv2" 2>&1 | grep libstd nicolashug@nicolashug-fedora-PF372ZT9
133766: find library=libstdc++.so.6 [0]; searching
133766: trying file=/home/nicolashug/.miniconda3/envs/codec/lib/python3.11/site-packages/cv2/../opencv_python.libs/libstdc++.so.6
133766: trying file=/home/nicolashug/.miniconda3/envs/codec/bin/../lib/libstdc++.so.6
133766: calling init: /home/nicolashug/.miniconda3/envs/codec/bin/../lib/libstdc++.so.6
133766: calling fini: /home/nicolashug/.miniconda3/envs/codec/bin/../lib/libstdc++.so.6 [0]
```
And in fact, if I `import torchcodec` BEFORE `import cv2` in the smoke test, the smoke test runs fine!!
```diff=
~/dev/torchcodec (main*) » git diff -p | \cat nicolashug@nicolashug-fedora-PF372ZT9
diff --git a/test/decoders/manual_smoke_test.py b/test/decoders/manual_smoke_test.py
index 07869c5..9690d99 100644
--- a/test/decoders/manual_smoke_test.py
+++ b/test/decoders/manual_smoke_test.py
@@ -1,7 +1,7 @@
import os
-import cv2
import torchcodec
+import cv2
decoder = torchcodec.decoders._core.create_from_file(
os.path.dirname(__file__) + "/resources/nasa_13013.mp4"
```
```
~/dev/torchcodec (main*) » python test/decoders/manual_smoke_test.py && echo $? 130 ↵ nicolashug@nicolashug-fedora-PF372ZT9
0
```
**So why is opencv loading the conda libstd?**
This is still somewhat of a mystery to me but running
```bash=
LD_DEBUG=all python -c "import cv2" > all 2>&1
```
we see
```
944879: file=libstdc++.so.6 [0]; needed by /home/nicolashug/.miniconda3/envs/codec/lib/python3.11/site-packages/cv2/cv2.abi3.so [0]
944879: find library=libstdc++.so.6 [0]; searching
944879: search path=/home/nicolashug/.miniconda3/envs/codec/lib/python3.11/site-packages/cv2/../opencv_python.libs (RPATH from file /home/nicolashug/.miniconda3/envs/codec/lib/python3.11/site-packages/cv2/cv2.abi3.so)
944879: trying file=/home/nicolashug/.miniconda3/envs/codec/lib/python3.11/site-packages/cv2/../opencv_python.libs/libstdc++.so.6
944879: search path=/home/nicolashug/.miniconda3/envs/codec/bin/../lib (RPATH from file python)
944879: trying file=/home/nicolashug/.miniconda3/envs/codec/bin/../lib/libstdc++.so.6
```
in particular `(RPATH from file python)` is the part that is weird and I cannot explain it.
I don't understand why Python's `rpath` is used in the search path here.
Note that when doing just `import torchcodec`, python's rpath isn't used in the search path is
```
file=libstdc++.so.6 [0]; needed by /home/nicolashug/.miniconda3/envs/codec/lib/python3.11/site-packages/torch/lib/libtorch_python.so [0]
find library=libstdc++.so.6 [0]; searching
search path=/home/nicolashug/.miniconda3/envs/codec/lib/python3.11/site-packages/torch/lib (RUNPATH from file /home/nicolashug/.miniconda3/envs/codec/lib/python3.11/site-packages/torch/lib/libtorch_global_deps.so)
trying file=/home/nicolashug/.miniconda3/envs/codec/lib/python3.11/site-packages/torch/lib/libstdc++.so.6
search cache=/etc/ld.so.cache
trying file=/lib64/libstdc++.so.6
```
despite the fact that python's rpath *is indeed* used to load other SOs previously during execution, e.g. this one is loaded way before `libstd`:
```
file=libdl.so.2 [0]; needed by python [0]
find library=libdl.so.2 [0]; searching
search path=/home/nicolashug/.miniconda3/envs/codec/bin/../lib (RPATH from file python)
trying file=/home/nicolashug/.miniconda3/envs/codec/bin/../lib/libdl.so.2
search cache=/etc/ld.so.cache
trying file=/lib64/libdl.so.2
```
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