ConcurrentModificationException will be reported when concurrent

[Jude95]

java.util.ConcurrentModificationException
        java.base/java.util.LinkedHashMap$LinkedHashIterator.nextNode(LinkedHashMap.java:756)
        java.base/java.util.LinkedHashMap$LinkedKeyIterator.next(LinkedHashMap.java:778)
        io.github.reactivecircus.cache4k.RealCache.expireEntries(RealCache.kt:174)
        io.github.reactivecircus.cache4k.RealCache.put(RealCache.kt:120)

[Shabinder]

+1:

java.util.ConcurrentModificationException at 
java.util.LinkedHashMap$LinkedHashIterator.nextNode(LinkedHashMap.java:760) at
java.util.LinkedHashMap$LinkedKeyIterator.next(LinkedHashMap.java:782) at
kotlin.collections.CollectionsKt___CollectionsKt.firstOrNull(_Collections.kt:272) at
io.github.reactivecircus.cache4k.RealCache.evictEntries(RealCache.kt:206) at
io.github.reactivecircus.cache4k.RealCache.put(RealCache.kt:140)

[ychescale9]

I think we need to revert back to using stately which is thread-safe on JVM.

[Shabinder]

@ychescale9 will you be making a release anytime soon ?

[ychescale9]

I'll try to find some time in the coming weeks.

[luca992]

So I'm having issues with cache4k and ConcurrentModificationExceptions caused by stately on jvm.

Ktor's io.ktor.util.collections.ConcurrentMap seems to be stable, maybe their implementation could be used instead?

[ychescale9]

Thanks, will look into it.

[hoc081098]

+1 for Ktor Utils Collections 😊

[ychescale9]

looks like ktor's ConcurrentMap just delegates to ConcurrentHashMap on JVM which I've done in https://github.com/ReactiveCircus/cache4k/pull/39, though there are still some linearizability issues surfaced by Lincheck. Maybe we can land that change now and deal with the remaining issues later as they are not regressions.

[ychescale9]

Just released 0.13.0 with ConcurrentHashMap on JVM. Please let me know if this fixes the issue.