Greetings,
we have came across a resource leak involving ScanQueryIterator
instances.
The code presumably causing the leak is along the following lines:
----
public List<Cache.Entry<String, Entity>> someMethod() {
Iterator<Cache.Entry<String, Entity>> iter = someIgniteCache.iterator();
List<Cache.Entry<String, Entity>> entities = new ArrayList<>();
while (iter.hasNext()) {
entities.add(iter.next());
}
return entities;
----
I can assess from multiple heap dumps that none of the ScanQueryIterator
instances gets garbage collected and all remain hard referenced from
locIters HashSet of GridCacheQueryManager overseeing someIgniteCache.
The iterator returned from someIgniteCache.iterator() is closable and
when explicitly calling close(), the hard reference gets removed from
locIters as expected, but the code above does not do that.
I cannot figure out whether the underlying ScanQueryIterator should be
automatically removed from locIters or not. There is also
WeakQueryCloseableIterator for which weak references are handled
somewhat automatically.
As it stands, the above code generates millions of not collectable
ScanQueryIterator instances after few weeks which we cannot get rid of
by any other means than JVM restart.
Is the code above breaking the contract of the iterator or is this an
Ignite issue?
Many thanks for any pointers.
Kind regards,
Kamil Mišúth
