#22086: Building of template nodelist inside cache blocks
--------------------------------------+------------------------------------
Reporter: HenrikOssipoff | Owner: nobody
Type: Cleanup/optimization | Status: new
Component: Template system | Version: 1.6
Severity: Normal | Resolution:
Keywords: template, cache | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
--------------------------------------+------------------------------------
Comment (by HenrikOssipoff):
You are absolutely right - at some point the cached node will need to be
rendered, at which point the nodelist inside the cached block will become
irrelevant - it will just load whatever is cached instead and ignore the
underlying tree.
But the tree still exists under the cached block until that point, and
that seems to be the performance bottleneck we're experiencing, the fact
that the tree needs to be built.
I've attached two of our template files to perhaps give a better
understanding. `menu_dk.html` is being included from our `base.html`
template, which forms the basis of all of our other templates. If you look
at that template, it's mostly just a cache block with other files included
within that cache block. So far so good.
Then comes one of the included files, `games.html`. If you look through a
bit of that, you see that nearly everything in it is custom template tags,
namely `url-translate` and `facet-translate`. We know this is an ugly way
to do it, but it's needed for our application at the moment - each of
these tags generates a node that will, in their `render()`, do a look-up
in our product catalogue to find the correct translation for whatever
language we're showing. No code of value is in the nodes' `__init__`.
From my findings, it is the sheer number of nodes in the sub-tree of nodes
inside the cache block that makes the template slow, even when the whole
block is in fact cached. Sure, the nodes aren't rendered, but they still
exist in the tree, causing up to 100ms to 200ms of extra time for our
application.
In our particular case, it seems it would be an optimization if we could
somehow tell the cache block to only built its inside nodelist if there
didn't exist a valid cache for the block. In most cases, this check would
likely take up more time than just building the tree, while in extreme
cases of alot of nodes inside the cache block, it would be an
optimization.
Hope this made it more clear, otherwise I'll be happy to provide more code
if need be.
--
Ticket URL: <https://code.djangoproject.com/ticket/22086#comment:2>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.
--
You received this message because you are subscribed to the Google Groups
"Django updates" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to django-updates+unsubscr...@googlegroups.com.
To post to this group, send email to django-updates@googlegroups.com.
To view this discussion on the web visit
https://groups.google.com/d/msgid/django-updates/072.271f9614c57dcb93560d16944f617078%40djangoproject.com.
For more options, visit https://groups.google.com/groups/opt_out.
