Hi, Le ven. 17 janv. 2020 à 20:11, Frank Millman <fr...@chagford.com> a écrit :
> It works perfectly. However, some pdf's can be large, and there could be > concurrent requests, so I wanted to minimise the memory footprint. So I > tried passing the client_writer directly to the handler - > > await pdf_handler(client_writer) > client_writer.write(b'\r\n') > > It works! ReportLab accepts client_writer as a file-like object, and > writes to it directly. I cannot use chunking, so I just let it do its > thing. > > Can anyone see any problem with this? > > If the socket is slower than the PDF generation (which is probably always the case, unless you have a very fast network), it will still have to be buffered in memory (in this case in the writer buffer). Since writer.write is non-blocking but is not a coroutine, it has to buffer. There is an interesting blog post about that here that I recommend reading: https://lucumr.pocoo.org/2020/1/1/async-pressure/ Unfortunately, there is no way to avoid buffering the entire pdf in memory without modifying reportlab to make it async-aware. This version is still better than the one with BytesIO though because in that version the pdf was buffered twice, once in BytesIO and once in the writer, although you can fix that by using await writer.drain() after each write and then the two versions are essentially equivalent. Regards, Maxime. -- https://mail.python.org/mailman/listinfo/python-list
