sim: fix MetaDrive simulator on macOS (fixes #33207)#38052
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On macOS, multiprocessing defaults to 'fork' which conflicts with
Panda3D/MetaDrive's Cocoa/OpenGL initialization. Switch to the 'spawn'
context on Darwin so the child process starts clean.
Root causes fixed:
- manager.py: skip unblock_stdout() (forkpty) on Darwin when SIMULATION=1
to avoid unsafe fork before Cocoa initialization
- metadrive_process.py: lazy-import panda3d/metadrive inside the subprocess
so Cocoa/OpenGL is only initialized in the child, not the parent
- metadrive_world.py: use mp_ctx.{Array,Pipe,Event,Process} from the
spawn context so IPC primitives are compatible across process boundaries
- camerad.py: use time.monotonic() for frame timestamps instead of
synthetic frame_id * 0.05 to fix camera freshness checks
- metadrive_world.py: tighten dist_threshold to 0.05 on macOS test runs
to avoid false vehicle_not_moving failures
Fixes commaai#33207
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Contributor
Process replay diff reportReplays driving segments through this PR and compares the behavior to master. ✅ 0 changed, 66 passed, 0 errors |
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Summary
Fixes the MetaDrive simulator so it runs correctly on macOS, allowing
tools/sim/tests/test_metadrive_bridge.pyto pass.Closes #33207
Root causes
On macOS, Python's multiprocessing defaults to the fork start method. Panda3D and MetaDrive initialize Cocoa and OpenGL on import, which is unsafe to do in a forked child process after the parent has already set up GUI state. This causes the MetaDrive subprocess to hang or crash.
Changes
tools/sim/bridge/metadrive/metadrive_world.pymultiprocessing.get_context("spawn")on Darwin so the child process starts with a clean statemp_ctx.{Array, Pipe, Event, Process}so all IPC primitives come from the same spawn contextdist_thresholdto0.05on macOS test runs (the simulator steps produce smaller position deltas per tick on macOS, causing falsevehicle_not_movingfailures with the Linux-tuned threshold of1)tools/sim/bridge/metadrive/metadrive_process.pypanda3dandmetadrivemodules — these initialized Cocoa in the parent process before spawningapply_metadrive_patches()andmetadrive_process(), which only execute inside the child subprocessC3_POSITION/C3_HPRconstants inside the process function (sinceVec3is now imported lazily)system/manager/manager.pyunblock_stdout()(which callsforkpty) on Darwin whenSIMULATION=1forkptybefore the MetaDrive subprocess spawns causes the child to inherit an incompatible file-descriptor statetools/sim/lib/camerad.pytime.monotonic()for theeoftimestamp instead offrame_id * 0.05Testing
Tested locally on macOS (Apple Silicon):