Directly use psutil to get total system memory

qiskit_aer/backends/backend_utils.py

@@ -16,16 +16,18 @@
 """
 import os
 from math import log2
-from qiskit.utils import local_hardware_info
+
+import psutil
 from qiskit.circuit import QuantumCircuit
 from qiskit.compiler import assemble
 from qiskit.qobj import QasmQobjInstruction
 from qiskit.result import ProbDistribution
 from qiskit.quantum_info import Clifford
+
 from .compatibility import Statevector, DensityMatrix, StabilizerState, Operator, SuperOp
 
 # Available system memory
-SYSTEM_MEMORY_GB = local_hardware_info()["memory"]
+SYSTEM_MEMORY_GB = psutil.virtual_memory().total / (1024**3)
 
 # Max number of qubits for complex double statevector
 # given available system memory

qiskit_aer/backends/statevector_simulator.py

@@ -16,7 +16,8 @@
 import copy
 import logging
 from warnings import warn
-from qiskit.utils import local_hardware_info
+
+import psutil
 from qiskit.providers.options import Options
 from qiskit.providers.models import QasmBackendConfiguration
 
@@ -364,7 +365,7 @@ def _validate(self, qobj):
         if n_qubits > max_qubits:
             raise AerError(
                 f"Number of qubits ({n_qubits}) is greater than max ({max_qubits}) "
-                f'for "{name}" with {int(local_hardware_info()["memory"])} GB system memory.'
+                f'for "{name}" with {int(psutil.virtual_memory().total / (1024**3))} GB system memory.'
             )
 
         if qobj.config.shots != 1:

qiskit_aer/backends/unitary_simulator.py

@@ -17,7 +17,8 @@
 import copy
 import logging
 from warnings import warn
-from qiskit.utils import local_hardware_info
+
+import psutil
 from qiskit.providers.options import Options
 from qiskit.providers.models import QasmBackendConfiguration
 
@@ -351,7 +352,7 @@ def _validate(self, qobj):
             raise AerError(
                 f"Number of qubits ({n_qubits}) is greater than "
                 f'max ({max_qubits}) for "{name}" with '
-                f"{int(local_hardware_info()['memory'])} GB system memory."
+                f"{int(psutil.virtual_memory().total / (1024**3))} GB system memory."
             )
         if qobj.config.shots != 1:
             logger.info('"%s" only supports 1 shot. Setting shots=1.', name)

releasenotes/notes/psutil-added-ffb2a4b5956fa03d.yaml

@@ -0,0 +1,9 @@
+---
+upgrade:
+  - |
+    Added `psutil <https://pypi.org/project/psutil/>`__ as a dependency for
+    Qiskit Aer. This is used to determine the amount of physical resources
+    available. ``psutil`` is currently a dependency of Qiskit, which is a
+    requirement for Qiskit Aer, so ``psutil`` was effectively already required
+    for any ``qiskit-aer`` installation. But, as qiskit-aer is now using it
+    directly is now a direct dependency for ``qiskit-aer``.

setup.py

@@ -25,6 +25,7 @@
     "qiskit>=0.44.0",
     "numpy>=1.16.3",
     "scipy>=1.0",
+    "psutil>=5",
 ]
 
 classifiers = [