Does this IOC load any other EPICS drivers or device support at all (other than the standard ones that come with Base)? Your configuration with multiple callback threads is unusual, and a lot of device/driver support might not
have been written or tested with the thought that there could more than one such callback in mind, so any such support code might be contributing to this issue.
I agree that this seems like a possible cause.
However, for the record:
With ITER IOCs (virtualized as well as on bare-metal), running parallel callback threads has been the default for years, so I would not call it unusual. It depends.
Obviously, the drivers we use are few and well-tested.
Cheers,
~Ralph
