don't cache 1000 operations => don't leak RAM ... also cf. https://github.com/libvips/pyvips/issues/88

pyvipstest.py

#!/usr/bin/env python3

import os.path
import pyvips

infilepath = '/path/to/file.pdf'
basename = os.path.basename(infilepath).split('.')[0]
infile = open(infilepath, 'rb').read()

pyvips.voperation.cache_set_max(10) # 0 = no parallelisation at all
pdf = pyvips.Image.pdfload_buffer(infile, n=-1, sequential=True)
npages = pdf.get('n-pages')

for i in range(1, npages):
    print('.', end='', flush=True)
    outfilepath = f"/tmp/{basename}_page{i:03}.png"
    image = pyvips.Image.pdfload_buffer(infile, page=i, dpi=300, scale=1.0, sequential=True)
    open(outfilepath, 'wb').write(image.write_to_buffer('.png'))

print()