[jira] [Created] (IGNITE-12375) Inconsistent persistent cache behaviour: containsKey returns false on a key returned by iterator

["Matija Polajnar (Jira)" <ji...@apache.org>]

Matija Polajnar created IGNITE-12375:
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             Summary: Inconsistent persistent cache behaviour: containsKey returns false on a key returned by iterator
                 Key: IGNITE-12375
                 URL: https://issues.apache.org/jira/browse/IGNITE-12375
             Project: Ignite
          Issue Type: Bug
    Affects Versions: 2.7.6, 2.7
            Reporter: Matija Polajnar
         Attachments: ignite-bug.zip

On a fairly complex spring boot application using embedded Ignite persistent storage, we've managed (multiple times) to get into a situation where some persistent caches start behaving weirdly. The symptoms are such: caches' {{iterator()}} method returns the elements we previously put into caches as expected. {{size()}} also returns the expected value. But {{containsKey(x)}} and {{get(x)}} return {{false}} and {{null}} respectively for some (or all) keys that are expected to be in the cache and are even returned by the {{iterator()}}.

The problem never starts occurring mid-run, but always after cluster restarts; not at all always, and we suspect a necessary precondition is that cache configurations are slightly changed, like having modified QueryEntities and such. We also suspect this only happens on single-node clusters, so it might be related to IGNITE-12297, but the workaround that works for that problem does not fix the problem described here.

The caches in question then cannot be repaired short of destroying and re-creating them and re-importing data.

 

We tried and failed to reproduce the problem from scratch in a small demo application. We managed, however, to grab a {{work}} directory from our application after corruption and then create a demo application with a minimal set of classes needed to demonstrate the issue on reading (after corruption is already present).

I'm attaching a zip file with the code (along with a maven pom.xml) and the corrupted work directory. You can directly execute the demo by issuing {{mvn compile exec:java}}, which will execute the {{care.better.demo.ignitebug.BugApp}} class. In this class there's this method:

{code:java}
    private static void replicateProblem(IgniteCache<Object, Object> cache) {
        int seen = 0;
        Iterator<Cache.Entry<Object, Object>> entryIterator = cache.iterator();
        while (entryIterator.hasNext()) {
            Object key = entryIterator.next().getKey();
            if (!cache.containsKey(key) || cache.get(key) == null) {
                LOG.error("UNSEEN KEY: {}", key);
            } else {
                seen++;
            }
        }
        LOG.info("Size {}, seen {}.", cache.size(), seen);
    }
{code}
 
After execution you will note log records like this one: ERROR care.better.demo.ignitebug.BugApp.replicateProblem - UNSEEN KEY: QueueKey{affinityKey=PartyIdArg{namespace='ЭМИАС Медработники', id='222'}, entryId=c059b587-78d3-4c75-b64f-8575ae3d2318}

We had no success in trying to find any lead while debugging through Ignite source code so we kindly ask your assistance in hunting down this bug and, until it is fixed, suggesting any possible work-around should this occur in a production environment (it has not so far) where it is not practical to dump all data from some cache into a file to be able to destroy, re-create and re-import it.



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