Make PrimitiveJob serializable (#12963)

* Make PrimtiveJob serializable

* fix style

* fix init param order & ignore pylint

* add reno

* Remove default none

* Add comment in _prepare_dump()

* Update qiskit/primitives/primitive_job.py

Co-authored-by: Takashi Imamichi <[email protected]>

* formatting

* Update releasenotes/notes/serialize-primitive-job-aa97d0bf8221ea99.yaml

Co-authored-by: Takashi Imamichi <[email protected]>

* implement __getstate__ and __setstate__

* lint

* Update releasenotes/notes/serialize-primitive-job-aa97d0bf8221ea99.yaml

Co-authored-by: Takashi Imamichi <[email protected]>

* Update test/python/primitives/test_primitive_job.py

Co-authored-by: Takashi Imamichi <[email protected]>

---------

Co-authored-by: Takashi Imamichi <[email protected]>
Co-authored-by: Takashi Imamichi <[email protected]>

Author: kt474

qiskit/primitives/containers/data_bin.py

@@ -103,9 +103,6 @@ def __init__(self, *, shape: ShapeInput = (), **data):
     def __len__(self):
         return len(self._data)
 
-    def __setattr__(self, *_):
-        raise NotImplementedError
-
     def __repr__(self):
         vals = [f"{name}={_value_repr(val)}" for name, val in self.items()]
         if self.ndim:

qiskit/primitives/primitive_job.py

@@ -35,6 +35,8 @@ def __init__(self, function, *args, **kwargs):
         super().__init__(str(uuid.uuid4()))
         self._future = None
         self._function = function
+        self._result = None
+        self._status = None
         self._args = args
         self._kwargs = kwargs
 
@@ -46,19 +48,36 @@ def _submit(self):
         self._future = executor.submit(self._function, *self._args, **self._kwargs)
         executor.shutdown(wait=False)
 
+    def __getstate__(self):
+        _ = self.result()
+        _ = self.status()
+        state = self.__dict__.copy()
+        state["_future"] = None
+        return state
+
+    def __setstate__(self, state):
+        self.__dict__.update(state)
+        self._future = None
+
     def result(self) -> ResultT:
-        self._check_submitted()
-        return self._future.result()
+        if self._result is None:
+            self._check_submitted()
+            self._result = self._future.result()
+        return self._result
 
     def status(self) -> JobStatus:
-        self._check_submitted()
-        if self._future.running():
-            return JobStatus.RUNNING
-        elif self._future.cancelled():
-            return JobStatus.CANCELLED
-        elif self._future.done() and self._future.exception() is None:
-            return JobStatus.DONE
-        return JobStatus.ERROR
+        if self._status is None:
+            self._check_submitted()
+            if self._future.running():
+                # we should not store status running because it is not completed
+                return JobStatus.RUNNING
+            elif self._future.cancelled():
+                self._status = JobStatus.CANCELLED
+            elif self._future.done() and self._future.exception() is None:
+                self._status = JobStatus.DONE
+            else:
+                self._status = JobStatus.ERROR
+        return self._status
 
     def _check_submitted(self):
         if self._future is None:

releasenotes/notes/serialize-primitive-job-aa97d0bf8221ea99.yaml

@@ -0,0 +1,5 @@
+---
+features_primitives:
+  - |
+    To make :class:`.PrimitiveJob` serializable, :class:`.DataBin` has been 
+    updated to be pickleable. As a result, :class:`.PrimitiveResult` is now also pickleable.

test/python/primitives/test_primitive_job.py

@@ -0,0 +1,51 @@
+# This code is part of Qiskit.
+#
+# (C) Copyright IBM 2025.
+#
+# This code is licensed under the Apache License, Version 2.0. You may
+# obtain a copy of this license in the LICENSE.txt file in the root directory
+# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
+#
+# Any modifications or derivative works of this code must retain this
+# copyright notice, and modified files need to carry a notice indicating
+# that they have been altered from the originals.
+
+"""Tests for PrimitiveJob."""
+
+import pickle
+from test import QiskitTestCase
+
+import numpy as np
+from ddt import data, ddt
+
+from qiskit import QuantumCircuit
+from qiskit.primitives import PrimitiveJob, StatevectorSampler
+
+
+@ddt
+class TestPrimitiveJob(QiskitTestCase):
+    """Tests PrimitiveJob."""
+
+    @data(1, 2, 3)
+    def test_serialize(self, size):
+        """Test serialize."""
+        n = 2
+        qc = QuantumCircuit(n)
+        qc.h(range(n))
+        qc.measure_all()
+        sampler = StatevectorSampler()
+        job = sampler.run([qc] * size)
+        obj = pickle.dumps(job)
+        job2 = pickle.loads(obj)
+        self.assertIsInstance(job2, PrimitiveJob)
+        self.assertEqual(job.job_id(), job2.job_id())
+        self.assertEqual(job.status(), job2.status())
+        self.assertEqual(job.metadata, job2.metadata)
+        result = job.result()
+        result2 = job2.result()
+        self.assertEqual(result.metadata, result2.metadata)
+        self.assertEqual(len(result), len(result2))
+        for sampler_pub in result:
+            self.assertEqual(sampler_pub.metadata, sampler_pub.metadata)
+            self.assertEqual(sampler_pub.data.keys(), sampler_pub.data.keys())
+            np.testing.assert_allclose(sampler_pub.join_data().array, sampler_pub.join_data().array)