[jira] [Created] (IGNITE-15962) CacheEntryRemovedListener makes the PUT operation to send ENTRY CREATED events

["Alexey Kukushkin (Jira)" <ji...@apache.org>]

Alexey Kukushkin created IGNITE-15962:
-----------------------------------------

             Summary: CacheEntryRemovedListener makes the PUT operation to send ENTRY CREATED events
                 Key: IGNITE-15962
                 URL: https://issues.apache.org/jira/browse/IGNITE-15962
             Project: Ignite
          Issue Type: Improvement
    Affects Versions: 2.11
            Reporter: Alexey Kukushkin
         Attachments: CacheContinuousQueryEntry-HeapDump.png, CacheContinuousQueryEntry-StackTrace.png, EventListenerHeapUsage.java, IgniteServer.java, build.gradle

{{CacheEntryRemovedListener}} configured with {{MutableCacheEntryListenerConfiguration.isOldValueRequired = false}} makes the {{Cache#put}} operation to send {{CREATED}} events attached to the "Update" message. This is inefficient when working with large objects: our application running with limited heap memory fails with {{java.lang.OutOfMemoryError: Java heap space}} after executing a {{PUT}} operation since the entry referencing the object is "stuck" on the heap.

h2. Reproducer

h3. Steps
We need two Ignite server nodes to demonstrate the problem. A cache is deployed on both the nodes and both the nodes listen to the {{ENTRY REMOVED}} events. Both the nodes disable fetching the {{CacheEntryEvent#getOldValue}} by setting {{MutableCacheEntryListenerConfiguration.isOldValueRequired = false}}

# Build and run the attached  [^IgniteServer.java]. This server is configured like described above and runs until manually terminated.
# Build the run the attached test  [^EventListenerHeapUsage.java] . This test:
## Starts another server configured like described above
## Puts a large object taking 35% of the free memory. This is done in an isolated scope so the memory after the operation is garbage collected,
## Attempts to allocate 70% of the heap.

h3. Expected
The last "allocate 70% of the heap" operation should succeed. 

h3. Actual
{noformat}
Caused by: java.lang.OutOfMemoryError: Java heap space
	at apache.ignite.issues.EventListenerHeapUsage.entryRemovedEventListenerFetchesValueOnHeap(EventListenerHeapUsage.java:33)
{noformat}

h2 Analysis
For some reason configuring the event listener makes the {{IgniteCache#put}} operation to create and attach an instance of {{CacheContinuousQueryEntry}} with {{evtType=CREATED}} and {{newObject}} referencing the entry. 

The attached heap dump !CacheContinuousQueryEntry-HeapDump.png! collected on the {{OutOfMemoryError}} demonstrates the large object "stuck" on the heap.

The attached {{CacheContinuousQueryEntry}} initialization  !CacheContinuousQueryEntry-StackTrace.png!  proves the {{ENTRY CREATED}} event is being created even though we did not configure it.

It seems wrong that Ignite needs to attached the {{ENTRY CREATED}} event to the "update" message. Please enhance Ignite to not be doing that or explain why Ignite must do that.



--
This message was sent by Atlassian Jira
(v8.20.1#820001)