playframework/playframework

`Play.XML` should use ThreadLocal SAXParser

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#6939 opened on Feb 4, 2017

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 (9 comments) (0 reactions) (0 assignees)Scala (12,623 stars) (4,032 forks)batch import
help wanted

Description

Apache xerces uses a lot of Class.forName to create SaxParser object, which will call ClassLoader.loadClass for every xml parsing.

And this will block each other, then leads to bad performance for a high load system.

Contributor guide

Tech stack
scalajava
Domain
backendperformance
Issue type
performance
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Basic Java XML parsingPlay Framework module structure
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30
Research direction
Locate the Play.XML module in the repository, likely under framework/src/play/src/main/scala/play/libs/. Identify where SAXParser is created for each parsing call. Replace with a ThreadLocal<SAXParser> instance to avoid repeated class loading. Review existing comments for any alternative approaches or concerns. Test performance under high load.