id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
33245	utils.urlize isn't thread-safe	Tim McCurrach	nobody	"Since [changeset:""e567670b1abe61af4acfaa6a6a7e92a7acfa8b00"" e567670b] `utils.urlize` isn't thread safe!

=== To replicate bug: ===

1. Write 2 views that both use the `urlizetrunc` tag a large number of times (between 10^4^ and 10^5^ was enough on my computer). 
2. Use different url length limits (for truncation) for each view
3. Load the 2 views simultaneously

The resulting pages will have inconsistent url limits, as the `trim_url_limit` value from one view leaks over to the other. 

=== The cause ===
Since `urlize` was changed to become class-based `trim_url_limit`, `nofollow`, `autoescape`, and `trim_url_limit`  are stored as instance attributes. `Urlizer` is instantiated just once and then used within `urlize` which allows for these values to be shared between function calls.

=== The solution ===
 - The obvious solution would be to pass the values listed above directly to `handle_word` so that they are not stored on the instance.
 - My only question is: Does removing these values from the class instance nullify the ease of customisation the original ticket brought about? If this is the case, the better solution might just be to revert the change.
 - An alternative approach would be to create a new instance of `Urlizer` on each call of `urlize`, but since this can be called many times in a single request, this would likely have a performance impact.
"	Bug	new	Utilities	dev	Normal				Unreviewed	0	0	0	0	0	0