HazelCast Quirks

Having had issues with hazelcast/payara-micro, I did some digging and found some quirks.

Iterate over cache with exactly one element

This fails consistently when there's only one element in the cache

for (Iterator<Cache.Entry> iterator = cache.iterator() ; iterator.hasNext() ;) {
    Cache.Entry next = iterator.next();

with: java.util.NoSuchElementException from com.hazelcast.cache.impl.AbstractClusterWideIterator.next

Set component of cache key has been cached before (serialized?)

If a Set<> cache key (or a complex key with a Set<> component) has been stored in a cache, it does not match even when .hashCode() returns the same value and .equals(...) returns true.

curl http://localhost:8080/hazelcast-quirks-1.0-SNAPSHOT/false

1st run:

• Cache miss on cache-1, then generated a Set, and stores it.
• Cache miss on cache-2 (newly generated set as key) generated a value and stores it
• Dumping cache fails (due to the 1 element issue)

2nd run:

• Cache hit on cache-1
• Expected cache hit on cache-2, but gets cache-miss, generated a new value and stores it
• Dumping cache now return 2 entries both with the values from 2nd run and same key

3rd run:

• Cache hit on cache-1
• Cache hit on cache-2
• Still 2 (identical) entries in

If a copy is made of the set, and that is used for cache-key in cache-2

curl http://localhost:8080/hazelcast-quirks-1.0-SNAPSHOT/true

1st run: exactly as 1st run before

2nd run:

• Cache hit on cache-1
• Cache hit on cache-2
• Still one element in the cache, dump fails

How to run service

mvn clean package && java -jar payara-micro-5.183.jar --deploy target/hazelcast-quirks-1.0-SNAPSHOT.war