How do I make this function thread safe?

Fri Jun 1 02:30:34 UTC 2018

On Thursday, 31 May 2018 at 19:26:12 UTC, Dr.No wrote:
> My application create some HTML which is then converted to PDF 
> by wkhtmltopdf library. I'm trying to figure out how make the 
> PDF generation run parallel, currently, it's running linearly.

It looks like wkhtmltopdf does not support multithreaded use; see 
here:

https://github.com/wkhtmltopdf/wkhtmltopdf/issues/1711

So, if you want to run the conversions in parallel, you will have 
to use separate processes.