rootvector2 opened a new pull request, #285:
URL: https://github.com/apache/commons-jxpath/pull/285

   Thanks for your contribution to [Apache 
Commons](https://commons.apache.org/)!
   
   - [x] Read the [contribution guidelines](CONTRIBUTING.md) for this project.
   - [ ] Read the [ASF Generative Tooling 
Guidance](https://www.apache.org/legal/generative-tooling.html) if you use 
Artificial Intelligence (AI).
   - [ ] I used AI to create any part of, or all of, this pull request. Which 
AI tool was used to create this pull request, and to what extent did it 
contribute?
   - [ ] Run a successful build using the default 
[Maven](https://maven.apache.org/) goal with `mvn`; that's `mvn` on the command 
line by itself.
   - [x] Write unit tests that match behavioral changes, where the tests fail 
if the changes to the runtime are not applied.
   - [x] Write a pull request description that is detailed enough to understand 
what the pull request does, how, and why.
   - [x] Each commit in the pull request should have a meaningful subject line 
and body.
   
   `DocumentContainer` keeps two static registries, `parsers` and 
`parserClasses`, as plain `HashMap`. `registerXMLParser` mutates them with 
`put`, and `getParser` (reached through `getValue` then `parseXML`) mutates 
`parsers` with `computeIfAbsent`, none of it synchronized, while the rest of 
the library already uses `ConcurrentHashMap` for the same kind of registry 
(`JXPathIntrospector`, `ValueUtils`). When two threads first parse a given 
model concurrently, or one thread registers a parser while another parses, they 
race on the shared map. I hit a `ConcurrentModificationException` thrown from 
`HashMap.computeIfAbsent` in `getParser`, and on other runs a corrupted map 
spinning forever in `resize`/`treeify` inside `registerXMLParser` at 100% CPU. 
Switching both fields to `ConcurrentHashMap` lines them up with the other 
registries and drops the race. The added test reproduces it: it fails on the 
current code with the `ConcurrentModificationException` and passes with the 
change.
   


-- 
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.

To unsubscribe, e-mail: [email protected]

For queries about this service, please contact Infrastructure at:
[email protected]

Reply via email to