Intermittent OOM error when running QiskitEngine

[hamidelmaazouz]

Describe the bug

ERROR:  [Experiment 0] Insufficient memory to run circuit circuit-313 using the statevector simulator.
Required memory: 524288M, max memory: 15981M

Describe what you expected to happen This failure is intermittent and happens when running the Qiskit-based QASM simulator unit tests in CI.

Add supporting information Intermittently observable in CI unit tests. The failure is closely related to the simulation method. Some methods are resource hungry.

Actions

• Deep dive and report about Qiskit's AerSimulator simulation methods
• Identify resource-hungry methods
• One workaround is simply add more memory to the GH runner. Although it's probably worthwhile to make simulation methods configurable in QAT so that it's easy to avoid expensive ones.

[hamidelmaazouz]

This bug is being addressed here: https://github.com/oqc-community/qat/pull/206. Cheers @lcauser-oqc