Possible memory leak following rendering

First off: awesome work with WeasyPrint, it’s super great !

We’re using WeasyPrint under django and are experiencing a memory usage issue. if we make a big pdf (~360 pages with graphics) at the moment we do document.render() the memory jumps up a lot (1.4G), the problem is that once the pdf is made and the request is finished the webserver is still hanging onto that slice of memory, it seems never to be released.

Is anyone aware of memory release issues using WeasyPrint ? the relevant code is here:

#low mem here
html = weasyprint.HTML(StringIO(html_string.encode('utf-8')), encoding='utf8', base_url='file://')
#low mem here
html.write_pdf(target=out_filename)
#high mem here
del html
gc.collect()
#high mem here still

maybe we should be spawning a new process to run WeasyPrint in for such large PDFs ? we’ve tried calling gc.collect() to no effect.

any ideas would be appreciated, cheers

-ivan

[jimr]

@excieve FWIW we pass --maxtasksperchild 10 to our celery worker command to avoid ever-growing memory footprint for workers using WeasyPrint. This restarts workers every ten tasks which works pretty well for our workload and means we don’t have any issues with memory consumption any more.

[excieve]

Thank you @liZe and @SimonSapin for looking into it!