Ferran - No, this is the right place. Noxx is suggesting a change to Django.
Noxx - it seems reasonable to improve Django here. You mentioned ASGI - did you check what the WSGI paths do? It may be that the newer ASGI code is simply less optimal. Would it be possible to reduce the workflow to a single write call? > This is indeed the question. Could you investigate further and perhaps come up with a patch? You're likely "the world expert" on this part of Django at this point, after all the profiling you've done. On Wed, May 11, 2022 at 5:44 PM Ferran Jovell <fer...@jovell.dev> wrote: > This is still the wrong place. Try django-users mailing list. > > El dc., 11 de maig 2022, 17:53, 'Noxx' via Django developers > (Contributions to Django itself) <django-developers@googlegroups.com> va > escriure: > >> Story >> >> Our application supports many file uploads. >> In normal circumstances, those files are only a few megabytes to of >> around 100MB. >> However, some uploads can be several GB in size (10-15GB and up). >> >> I know, that file uploads with such a size can be handled differently, >> e.g. using a seperate endpoint, allowing slow requests to be served >> seperately from the application etc. >> and only to reference those files in a final request. >> This solution would introduce some other problems regarding >> house-keeping, non-atomic requests etc, thus I want to ignore this >> workaround for now. >> Performance impact: >> <https://code.djangoproject.com/ticket/33699#Performanceimpact:> >> >> The impact can be best observed when uploading a file which is bigger in >> it's size, e.g. 1GB+. >> On my maschine it takes the client around 700ms to send the request to >> the application, but than waits around 1.5s for the final response. >> Of course, those numbers are dramatically influenced additionally in >> production by storage speed, file size, webserver (uvicorn/daphne/..), >> load-balancers etc. >> But the final take here is, that the server does some additional work >> after the client finished its request. >> In a production-like environment the numbers peaks to 4s (send request) >> and 16s (waiting for response) for the same file size. Uploading a 3GB >> file, the numbers are 11s and 44s. >> As you can see, the 44s are very near the default gateway timeout of >> Nginx and the hard-coded one of AWS load-balancers. >> As soon as the server needs more than 60s to create the response, the >> client will get a gateway timeout error. >> Workflow of file uploads: >> <https://code.djangoproject.com/ticket/33699#Workflowoffileuploads:> >> >> I'm not a Django-dev, so please correct me if I'm wrong. As far as I >> understand, the uploaded file is processed as the following: >> >> Given, that the application is running within an ASGI server, the whole >> request is received by the ASGIHandler. >> It's method #read_body creates a SpooledTemporaryFile. >> This temporary file contains the whole request body, including POST >> parameters and files. >> >> As soon as the request has been received (this is the point the client >> finished uploading the file) it is than transformed into an ASGIRequest. >> The ASGIRequest has #_load_post_and_files and #parse_file_upload as >> methods which parses the body into seperate files. >> This is done by reading the body (the temporary file) and iterating over >> them seperated by the POST seperator done by MultiPartParser. >> The generated chunks are than sent to upload handlers which process those >> files further on using #receive_data_chunk. >> The default upload handlers provided by Django will write those files to >> disc again, depending on their size. >> Problem <https://code.djangoproject.com/ticket/33699#Problem> >> >> The problem here is, that the uploaded file(s) are transformed and >> written as well as read multiple times. >> First the whole body is written into a SpooledTemporaryFile which is >> re-read using streams (LazyStream) just to be written once more by an >> upload handler. >> >> The impact is low if the uploaded file is small, but increases >> dramatically if the size is increased, the file hits the disc and/or the >> storage is slow. >> Optimization / Brainstorming >> <https://code.djangoproject.com/ticket/33699#OptimizationBrainstorming> >> >> Would it be possible to reduce the workflow to a single write call? >> E.g. if the ASGIHandler already splits the request body into seperate >> files, it would be possible to just forward the file pointers until the >> upload handlers needs to be called. >> Those handlers would be able to either use those files as-is or to >> re-read them if pre-processing is needed. >> >> In a best-case scenario, an user uploads a file whichis created as a >> temporary file in parallel. >> As soon as the request has been finished, the file is than moved to its >> final location (as already implemented by upload handlers by providing >> #temporary_file_path) >> The server would not need any time processing the request further on and >> would be able to sent the response within some milliseconds independent of >> the file size. >> The roundtrip time would be reduced by 2/3 and also the gateway timeout >> would be fixed. >> Environment <https://code.djangoproject.com/ticket/33699#Environment> >> >> We're using Django 4.0.4 with Gunicorn 20.1.0 and Uvicorn 0.17.6. >> Attachments <https://code.djangoproject.com/ticket/33699#Attachments> >> >> I've attached two flame graphs of a file upload which hopfully >> illustrates this issue. >> One is using the internal runserver (wsgi) and one of our (stripped) >> application using gunicorn+uvicorn (asgi) >> >> Final notes >> >> I'd by happy to get some thoughts and opinions on this issue and if this >> is even possible to change/implement. >> >> Cross-posted from https://code.djangoproject.com/ticket/33699 as ticket >> has been closed due to wrong place... >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Django developers (Contributions to Django itself)" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to django-developers+unsubscr...@googlegroups.com. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/django-developers/00b47caf-2810-487f-86c5-dcf52426299an%40googlegroups.com >> <https://groups.google.com/d/msgid/django-developers/00b47caf-2810-487f-86c5-dcf52426299an%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> > -- > You received this message because you are subscribed to the Google Groups > "Django developers (Contributions to Django itself)" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to django-developers+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/django-developers/CAEKh-snKLv4sd_QuoAcY7F4oo6GFM5MwMndJrZ-nz1VkXgqG%3Dg%40mail.gmail.com > <https://groups.google.com/d/msgid/django-developers/CAEKh-snKLv4sd_QuoAcY7F4oo6GFM5MwMndJrZ-nz1VkXgqG%3Dg%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "Django developers (Contributions to Django itself)" group. 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