Darrel Schneider created GEODE-9801:
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Summary: CachePerfStats.replicatedTombstonesSize and
nonReplicatedTombstonesSize are not accurate
Key: GEODE-9801
URL: https://issues.apache.org/jira/browse/GEODE-9801
Project: Geode
Issue Type: Bug
Components: core
Affects Versions: 1.12.0
Reporter: Darrel Schneider
This issue has been around since Geode 1.0.
CachePerfStats.replicatedTombstonesSize and nonReplicatedTombstonesSize are
supposed to help geode users figure out how much memory is being used by
tombstones. But because of some over sites in the sizing code they actual
amount of memory used by tombstones is significantly higher. Some of the
mistakes made:
1. A Tombstone is added to a ConcurrentLinkedQueue. This is accounted for as a
single objRef. But each add to a ConcurrentLinkedQueue add a Node instance so
you have the object header size plus two objRefs.
2. The size of the RegionEntry is not accounted for. The size of the key in
this entry is but most of the memory used is in the RegionEntry fields itself.
And the key, in some cases, is stored inline in primitive fields in the
RegionEntry so Tombstone.getSize should not be asking the RegionEntry for its
key and then sizing it but should instead just ask the RegionEntry for its
memory footprint. It can then figure out if it needs to size any of the objects
it references (like the key).
3. the Tombstone class it self accounts for all its fields but forgot about its
own object header.
To fix this have the Tombstone class add the following:
{code:java}
private static final TOMBSTONE_OVERHEAD =
JvmSizeUtils.memoryOverhead(Tombstone.class);
{code}
For the Node overhead on ConcurrentLinkedQueue add this:
{code:java}
private static final NODE_OVERHEAD =
JvmSizeUtils.roundUpSize(JvmSizeUtils.getObjectHeaderSize() +
2*JvmSizeUtils.getReferenceSize());
{code}
For RegionEntry add a new "memoryOverhead" method on RegionEntry and then
implement it in all the many leaf classes. You can do this by modifying
LeafRegionEntry.cpp and running generateRegionEntryClasses.sh. You will want
each class to have a private static final field that calls
JvmSizeUtils.memoryOverhead(<CLASSNAME>.class) and then decide at runtime if
the instance references other objects that should be sized (like key, value,
DiskId, etc.).
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