bonsai.crash.txt

There seems to be cases when Blender might crash too unexpectedly.
E.g. #6686 - during viewport render system is running out of resources and crashing without leaving blender.crash.txt, leaving everyone clueless. Which is arguably a bug in Blender (both crash and lack of any crash report), but at least we'll have a fallback for this case.

What bonsai.crash.txt does - it's created in system temp folder with the current Python traceback, just before some dangerous operation. If operation didn't crashed Blender, then file will be unlinked. If crash did occurred, it might be the only clue for users and devs on what actually happened.

src/bonsai/bonsai/bim/module/drawing/operator.py

@@ -460,7 +460,10 @@ class CreateDrawing(bpy.types.Operator):
             previous_format = context.scene.render.image_settings.file_format
             space.shading.type = "RENDERED"
             context.scene.render.image_settings.file_format = "PNG"
-            bpy.ops.render.opengl(write_still=True)
+
+            with tool.Blender.bonsai_crash_txt("render.opengl"):
+                bpy.ops.render.opengl(write_still=True)
+
             space.shading.type = previous_shading
             context.scene.render.image_settings.file_format = previous_format
 

src/bonsai/bonsai/tool/blender.py

@@ -25,6 +25,8 @@ import os
 import platform
 import subprocess
 import contextlib
+import tempfile
+import traceback
 import numpy as np
 import numpy.typing as npt
 from ifcopenshell import entity_instance
@@ -1758,3 +1760,35 @@ class Blender(bonsai.core.tool.Blender):
     def report_operator_errors(cls, operator: bpy.types.Operator, error_reports: list[str]) -> None:
         for report in error_reports:
             operator.report({"ERROR"}, report)
+
+    @classmethod
+    @contextlib.contextmanager
+    def bonsai_crash_txt(cls, s: str = "") -> Generator[Path, Any, None]:
+        """Create a temporary bonsai.crash.txt file the with current traceback.
+
+        Useful in case Blender crash might occur too unexpectedly (e.g. #6686),
+        and at least we'll have a slightest clue on what happened.
+
+        Intended to be used via `with` block.
+        `atexit` wouldn't work for this as crash breaks everything
+        and no callbacks are called.
+
+        :param s: Optional string to add at the top of the txt file.
+        """
+        # TODO: Indicate that crash occurred after Blender restart?
+
+        # Create a temp file with the traceback.
+        temp_dir = tempfile.gettempdir()
+        path = Path(temp_dir) / "bonsai.crash.txt"
+        traceback_ = "\n".join(traceback.format_stack())
+        output = ""
+        if s:
+            output += f"{s}\n\n"
+        time = datetime.now().isoformat()
+        output += f"Created at: {time} (local time).\n"
+        output += f"Traceback (most recent called last):\n{traceback_}"
+        path.write_text(output)
+        yield path
+
+        # Remove file if crash didn't happened.
+        path.unlink()