ScanFiles / Concurrent modification exception

[ahus1]

I've changed some configurations and ran a scan. I received the following exception once, then the scan continued as usual. I wasn't able to reproduce it yet.

2020-03-28 20:52:21,716 [2118245]   INFO - .idea.checkstyle.StaticScanner - Scanning current file(s). 
2020-03-28 20:52:21,737 [2118266]   WARN - a.checkstyle.checker.ScanFiles - An error occurred while scanning a file. 
java.util.ConcurrentModificationException
	at java.base/java.util.HashMap$HashIterator.nextNode(HashMap.java:1493)
	at java.base/java.util.HashMap$KeyIterator.next(HashMap.java:1516)
	at java.base/java.lang.Iterable.forEach(Iterable.java:74)
	at org.infernus.idea.checkstyle.checker.ScanFiles.fireCheckStarting(ScanFiles.java:115)
	at org.infernus.idea.checkstyle.checker.ScanFiles.call(ScanFiles.java:77)
	at org.infernus.idea.checkstyle.checker.ScanFiles.call(ScanFiles.java:33)
	at com.intellij.openapi.application.impl.ApplicationImpl$2.call(ApplicationImpl.java:274)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	at java.base/java.lang.Thread.run(Thread.java:834)

[jshiell]

Thank you! I would expect it's probably not reproducible except by chance - IDEA has been changing the concurrency model in the past few releases, with the goal of increasing IDE responsiveness. While this is great, it is showing the age of this plugin - a lot of the code was written when we could expect no or at least a much lower of concurrency, and so there's various bits of code that need fixing to deal with this. This appears to be one of them - it should be fixed in the next release.