Alexey Kukushkin created IGNITE-15962:
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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 withÂ
{{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.
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