#36520: Performance Regression in parse_header_params
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Reporter: David Smith | Owner: (none)
Type: Bug | Status: new
Component: HTTP handling | Version: dev
Severity: Release blocker | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Comment (by David Smith):
Yes, `get_params()` seems to be where most of the time is being spent.
The 5x claim I made above is just looking at this function. Other things
are happening in the ASV benchmarks, so the impact shown there is much
smaller. Maybe that's a good reason to suggest that even though this
function is much slower, it is small in the overall request/response
cycle. However, I think that as this is called with every request even
small gains are worth having.
I have done a bit more work on this. We could optimise for content types
that do not include parameters and avoid a lot of the work in this case.
Something like this:
I'm rather unsure how common parameters are. Some evidence would be useful
to avoid optimising for the wrong thing.
{{{
diff --git a/django/utils/http.py b/django/utils/http.py
index 1c7aec7141..111740cd02 100644
--- a/django/utils/http.py
+++ b/django/utils/http.py
@@ -326,6 +326,10 @@ def parse_header_parameters(line,
max_length=MAX_HEADER_LENGTH):
if max_length is not None and line and len(line) > max_length:
raise ValueError("Unable to parse header parameters (value too
long).")
+ if line and ";" not in line:
+ # No parameters, just return the content type.
+ return line.strip().lower(), {}
+
m = Message()
m["content-type"] = line
params = m.get_params()
}}}
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Ticket URL: <https://code.djangoproject.com/ticket/36520#comment:2>
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