System Information
Operating system: linux
Graphics card: amd
Blender Version
Broken: blender-3.0.0-alpha+master.4256eeeec4ca-linux.x86_64-release
Short description of error
Clicking "Create pose asset" button in the action editor hangs blender.
Exact steps for others to reproduce the error
Open attached blend file
Click "Create pose asset" in the sidebar of the action editor
Originally attached file:
Related to rB6e01b52100f3: Assets: temporarily apply pose when generating preview image, hangs here:
1 tbb::internal::custom_scheduler<tbb::internal::IntelSchedulerTraits>::receive_or_steal_task(long&, long) 0x3cf185a 2 tbb::internal::custom_scheduler<tbb::internal::IntelSchedulerTraits>::local_wait_for_all(tbb::task&, tbb::task *) 0x3cf2ad7 3 tbb::task::wait_for_all task.h 820 0x42b7977 4 tbb::internal::task_group_base::wait task_group.h 168 0x42b7de4 5 tbb_task_pool_work_and_wait task_pool.cc 251 0x10aca404 6 BLI_task_pool_work_and_wait task_pool.cc 500 0x10acaa2a 7 blender::deg::deg_evaluate_on_refresh deg_eval.cc 400 0x4031145 8 deg_flush_updates_and_refresh depsgraph_eval.cc 58 0x4003baf 9 DEG_evaluate_on_refresh depsgraph_eval.cc 75 0x4003c66 10 action_preview_render_prepare render_preview.c 950 0x6099cc3 11 action_preview_render render_preview.c 981 0x6099f19 12 icon_preview_startjob_all_sizes render_preview.c 1680 0x609ba14 13 ED_preview_icon_render render_preview.c 1788 0x609bda6 14 icon_set_image interface_icons.c 1426 0x4db87c6 15 ui_id_preview_image_render_size interface_icons.c 1945 0x4db9d7d 16 UI_icon_render_id interface_icons.c 1963 0x4db9e03 17 ED_asset_mark_id asset_mark_clear.cc 56 0x49f67ba 18 rna_ID_asset_mark rna_ID.c 674 0x45c0358 19 ID_asset_mark_call rna_ID_gen.c 1347 0x45c42eb
The problem lies with the evaluation of drivers that require evaluation in Python. This tries to lock the GIL, causing deadlock. This helped me create a minimal example (just a single bone, with one driver, referencing one other object). I'll attach it to the description.
@Roman (rwman) you can work around this issue by rewriting your shapekey driver. Currently it has the expression 1-((var-0.02)*2.5)**2. Because of the square, this cannot be evaluated by Blender's simple expression evaluator, and thus uses Python to evaluate the expression. This is what is currently hanging (and is a bug that should be fixed). Changing it to 1-((var-0.02)*2.5)*((var-0.02)*2.5) makes it actually compatible with the simple expression evaluator, avoid Python, and be faster and not hang. You can also rewrite it to 1 - 6.25 * (var - 0.02) * (var - 0.02) and make it a little bit faster.
The fix for this was reverted, see rBfc4603511704: Depsgraph: release GIL when evaluating the depsgraph.
The original commit + this additional change seems to fix both this bug and the render crash.
_PyThreadState_UncheckedGet() doesn't check if the current thread is actually holding the GIL.
diff --git a/source/blender/python/generic/bpy_threads.c b/source/blender/python/generic/bpy_threads.c index 57eb3a8..54548b8 100644 --- a/source/blender/python/generic/bpy_threads.c +++ b/source/blender/python/generic/bpy_threads.c @@ -29,10 +29,9 @@ /* analogue of PyEval_SaveThread() */ BPy_ThreadStatePtr BPY_thread_save(void) { - /* Use `_PyThreadState_UncheckedGet()`, instead of more canonical `PyGILState_Check()` or - * `PyThreadState_Get()`, to avoid a fatal error issued when a thread state is NULL (the thread - * state can be NULL when quitting Blender). */ - if (_PyThreadState_UncheckedGet()) { + /* Don't use `PyThreadState_Get()`, to avoid a fatal error issued when a thread state is NULL + * (the thread state can be NULL when quitting Blender). */ + if (PyGILState_Check()) { return (BPy_ThreadStatePtr)PyEval_SaveThread(); } return NULL;
Feel free to commit.
This was properly fixed by rBfe4286435c54, which includes the diff from @Brecht Van Lommel (brecht). Thanks Brecht!