Failed verification: ' fStageListeners.empty() ' -- Coding Error in onStageSet at line 517

[csyshing]

Hi,

I am debugging an error from a render farm job that was causing by this message in maya-usd:

Failed verification: ' fStageListeners.empty() ' -- Coding Error in onStageSet at line 517

Searching around the code and seems this variable fStageListeners has been used only in StagesSubject class, and it's not clear to me how come the verification failed at line 517?

maya-usd/lib/mayaUsd/ufe/StagesSubject.cpp

Lines 516 to 517 in dac1abb

	TF_VERIFY(g_StageMap.isDirty());
	TF_VERIFY(fStageListeners.empty());

by looking at the code, line 517 doesn't seem to affect anything else, the code still keep going forward regardless of the verification - is this severity level too high? Can we maybe lower it to be a warning instead?
Or if fStageListeners is critical, how about adding proper error handling / clean up?

Thanks,
Zhicheng

[kxl-adsk]

This is important to investigate issue. We are sending onStageInvalidate from dirty propagation, and after onStageSet from compute when the new stage is set. The error is telling us that something refreshed the map of all stages but with invalid data. This means that some consumers of this information (either read directly for proxy shape or via stage cache) have received incorrect information.

Most likely, something causes pull evaluation during dirty propagation. This is illegal in Maya's DG.

[csyshing]

Thanks @kxl-adsk , I will do some investigation for the consumer code then.