I'm not currently suffering from this. In the past with .NET I have definitely suffered from some long memory loads of DLLs.
The stuff I'm doing now is a lot of back end batch processing where how fast the initial response is is pretty negligible compared to a process that lasts for 10+ minutes. Just weighing in on the general design principle of long initial lazy loads in frameworks. -Ben On Sun, Mar 27, 2016 at 3:42 PM, Fred Stluka <[email protected]> wrote: > Ben, > > If lazy loading is causing you problems, here's good info on how to > force Django to load everything up front, by calling select_related() > and prefetch_related() in cases where you need to. And also how to > make that the default via use_for_related_fields and custom managers: > - https://docs.djangoproject.com/en/1.9/topics/db/optimization/ > > --Fred > ------------------------------ > Fred Stluka -- mailto:[email protected] <[email protected]> -- > http://bristle.com/~fred/ > Bristle Software, Inc -- http://bristle.com -- Glad to be of service! > Open Source: Without walls and fences, we need no Windows or Gates. > ------------------------------ > On 3/27/16 4:15 PM, [email protected] wrote: > > I'm not too familiar with the code you're referencing, but I'm personally > really annoyed by lazy loading. It has a tendency to make selenium tests > timeout inconsistently in CI, as well as give the impression to my bosses > that the app is slow rather than just the first load which is usually what > they see on new features. > > -Ben > > On Thursday, March 24, 2016 at 9:39:50 AM UTC-7, David Evans wrote: >> >> Hi all, >> >> Currently, middleware is initialized lazily on serving the first request, >> rather than on application start. There may well have been good reasons for >> this historically, but I don't think they apply any longer. Lazy >> initialization is unhelpful if a middleware class throws an error (e.g to >> report a misconfiguration) because the application will appear to start >> successfully and only later report the error when a request is made. >> >> I'd like to propose initializing middleware when `get_wsgi_application` >> is called. This solves the problem described above and, as far as I can >> tell, raises no backwards compatibility issues. >> >> More details on all this below. >> >> >> ### 1. Specific example of the problem >> >> I recently wrote an adapter for the WhiteNoise static file server so it >> could function as Django middleware as well as WSGI middleware ( >> https://github.com/evansd/whitenoise). WhiteNoise may be unusual in >> doing a non-trivial amount of work on initialization, but it doesn't seem >> unreasonable. When used as WSGI middleware any errors are triggered >> immediately on start up, but not so when used as Django middleware. This >> makes for a worse developer experience and an increased chance of >> deployment errors. >> >> >> ### 2. Reasons previously given for lazy initialization >> >> There was some brief discussion in this ticket 4 years ago: >> https://code.djangoproject.com/ticket/18577 >> >> The reason given there is that "resolving on first request makes most >> sense, especially for the case where you might not be serving requests at >> all". Presumably this refers to running non-http-related management >> commands. But in those cases we never instantiate a WSGI application anyway >> (wsgi.py is just never imported) so this is no reason not to initialize >> eagerly when constructing the WSGI application. (Of course, things may have >> been different 4 years ago.) >> >> Another reason is given in the comments in django.core.handles.wsgi: >> >> https://github.com/django/django/blob/3c1b572f1815c295878795b183b1957d0df2ca39/django/core/handlers/wsgi.py#L154 >> >> This says "Set up middleware if needed. We couldn't do this earlier, >> because settings weren't available". However `get_wsgi_application` (the >> only public WSGI API) now calls `django.setup()` before constructing the >> handler so settings are in fact available. >> >> >> ### 3. Proposed solution >> >> My proposal is simply to amend `get_wsgi_application` as follows: >> >> def get_wsgi_application(): >> django.setup(set_prefix=False) >> handler = WSGIHandler() >> handler.load_middleware() >> return handler >> >> It's possible that this logic could be moved into the handler's __init__ >> method. This caused no problems with existing application when I tried it, >> however it did cause problems with the test suite which seems to rely on >> the old behaviour in places. The above proposal passes all existing tests >> as is. >> >> >> ### 4. Backwards compatibility issues >> >> Middleware constructors have no means of accessing the request object or >> anything that depends on it. They are called right at the start of the >> handler's `__call__` method before the `request_started` signal is sent and >> before the `script_prefix` thread-local is set. Therefore it cannot matter, >> from the middleware class's perspective, whether it is instantiated before >> or after the first request comes in. >> >> >> I'm aware this issue probably isn't high on anyone else's priority list, >> but I think it would count as a genuine -- if small -- improvement to >> Django. >> >> Thanks, >> >> Dave >> > -- > 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 [email protected]. > To post to this group, send email to [email protected]. > Visit this group at https://groups.google.com/group/django-developers. > To view this discussion on the web visit > <https://groups.google.com/d/msgid/django-developers/f61a2b50-01e3-48ef-809f-82edc23d9da4%40googlegroups.com?utm_medium=email&utm_source=footer> > https://groups.google.com/d/msgid/django-developers/f61a2b50-01e3-48ef-809f-82edc23d9da4%40googlegroups.com > . > For more options, visit https://groups.google.com/d/optout. > > > -- > You received this message because you are subscribed to a topic in the > Google Groups "Django developers (Contributions to Django itself)" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/django-developers/iIm7M6aUJmU/unsubscribe > . > To unsubscribe from this group and all its topics, send an email to > [email protected]. > To post to this group, send email to [email protected]. > Visit this group at https://groups.google.com/group/django-developers. > To view this discussion on the web visit > https://groups.google.com/d/msgid/django-developers/56F861CF.8060909%40bristle.com > <https://groups.google.com/d/msgid/django-developers/56F861CF.8060909%40bristle.com?utm_medium=email&utm_source=footer> > . > > For more options, visit https://groups.google.com/d/optout. > -- *Ben Liyanage *|* Software Engineer *|* Rentlytics, Inc.* Phone: (410) 336-2464 | Email: [email protected] 1132 Howard Street, San Francisco CA 94107 Visit our Website <http://www.rentlytics.com> | Watch our Video <http://youtu.be/Pe_9KE_fj34> -- You received this message because you are subscribed to the Google Groups "Django developers (Contributions to Django itself)" group. 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