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Qiskit / qiskit-ibm-runtime

IBM Client for Qiskit Runtime
https://docs.quantum.ibm.com/api/qiskit-ibm-runtime
Apache License 2.0
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`Session.from_id` unexpectedly suppresses deprecation warnings. #1886

Open dcanuto opened 2 months ago

dcanuto commented 2 months ago

Desribe the bug

When Session.from_id is called, internally it calls cls(service, backend) to create a Session instance, with backend set to a string. Unless it's intentional to suppress warnings from Session.__init__ when called from Session.from_id, this should raise two deprecation warnings (one for passing a service and one for backend as a string), but raises none.

Steps to reproduce

First, create a session instance and grab the ID:

from qiskit_ibm_runtime import Session, QiskitRuntimeService

service = QiskitRuntimeService() # account info previously saved
backend = service.least_busy(operational=True, simulator=False)
session = Session(backend=backend)

session_id = session.session_id

Next, regenerate the session from its ID:

regenerated_session = Session.from_id(session_id, service) # produces no warnings

Expected behavior

Deprecation warnings raised for service and backend as a string, as for example when I use Session.__init__ directly:

backend = service.least_busy(operational=True, simulator=False)
session = Session(service=service, backend=backend.name)

/var/folders/7_/rsgnsxr55d32q72f3m991h5r0000gn/T/ipykernel_33497/3846134487.py:6: DeprecationWarning: The service parameter is deprecated as of qiskit-ibm-runtime 0.26.0 and will be removed no sooner than 3 months after the release date. The service can be extracted from the backend object so it is no longer necessary.
  session = Session(service=service, backend=backend.name)
/var/folders/7_/rsgnsxr55d32q72f3m991h5r0000gn/T/ipykernel_33497/3846134487.py:6: DeprecationWarning: Passing a backend as a string is deprecated as of qiskit-ibm-runtime 0.26.0 and will be removed no sooner than 3 months after the release date. Use the actual backend object instead.
  session = Session(service=service, backend=backend.name)

Suggested solutions

Not sure how to solve the problem in its entirety, but part of the issue seems to be how issue_deprecation_msg is used in Session.__init__. As used there, the stacklevel passed to warnings.warn is 3 (default value of 2, plus one), which works when a session is created via __init__ directly. In that case, the stack is: issue_deprecation_msg -> Session.__init__ -> caller. But when Session.from_id is used, the stack is too deep: issue_deprecation_msg -> Session.__init__ -> Session.from_id -> caller.

Additional Information

kt474 commented 2 months ago

@dcanuto thanks for noticing this, we'll have to refactor from_id()