Silpi,
I have seen similar LOCK errors with Metadata Integrators after 2 upgrades (I am not clear from above where you found this error). I raised an SAP incident but after the last upgrade and thought it was fixed but after upgrading to IS 4.2 SP5, it happened again.
With integrators, unfortunately, the 'workaround' is currently to delete the integrator and recreate. This does lose history (and can take a while).
regards
Adrian