cupy 9.5.0 memory leak and setDevice not working

cupy-mwe-client.py

from io import BytesIO

import requests

from imageio import imread

if __name__ == '__main__':
    url = 'http://localhost:5000/wrong-gpu-and-memory-leak'
    while True:
        resp = requests.get(url)
        b = BytesIO(resp.content)
        b.seek(0)
        im = imread(b, format='tiff')

cupy-mwe.py

"""LOWFSC server -- simulation server for PACE."""
from io import BytesIO

from imageio import imwrite
from flask import Flask, send_file

try:
    import cupy as cp
    from cupyx.scipy import fft as cpfft

    cp.cuda.runtime.setDevice(1)  # use the second GPU, "private"
    # cp.cuda.Device(1).use()
    # print('Using GPU', cp.cuda.runtime.getDevice())
    mempool = cp.get_default_memory_pool()
    pinned_mempool = cp.get_default_pinned_memory_pool()
except ImportError:
    pass


app = Flask('cupy-dev1-memleak-mwe')


@app.route('/wrong-gpu-and-memory-leak', methods=['GET'])
def foobar():
    a = cp.random.rand(512,512)
    b = cpfft.fftshift(cpfft.fft2(cpfft.ifftshift(a)))
    c = b.get()
    buf = BytesIO()
    imwrite(buf, c, format='tiff')
    buf.seek(0)
    return send_file(buf, mimetype='image/tiff')

info.txt

cupy 9.5.0
numpy 1.20.3
python 3.9.6
CUDA 10.2
GPU: Nvidia Titan XP (2x)
CPU: Intel(R) Xeon(R) Gold 6154 (2x)
... more as needed