implement __getstate__ and __setstate__

Author: t-imamichi

Diff for: qiskit/primitives/primitive_job.py

@@ -48,10 +48,15 @@ def _submit(self):
         self._future = executor.submit(self._function, *self._args, **self._kwargs)
         executor.shutdown(wait=False)
 
-    def _prepare_dump(self):
-        """This method allows PrimitiveJob to be serialized"""
+    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:

Diff for: 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 i in range(len(result)):
+            self.assertEqual(result[i].metadata, result2[i].metadata)
+            self.assertEqual(result[i].data.keys(), result2[i].data.keys())
+            np.testing.assert_allclose(result[i].join_data().array, result2[i].join_data().array)