Dan Smith created GEODE-8671:
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Summary: Two threads calling get and retrieve the same
PdxInstance, resulting in corruption
Key: GEODE-8671
URL: https://issues.apache.org/jira/browse/GEODE-8671
Project: Geode
Issue Type: Improvement
Components: regions
Reporter: Dan Smith
Even if copy-on-read is set to true, two threads calling get on a partitioned
region can end up with the same PdxInstance object.
This is problematic because some PdxInstances methods are not thread safe.
Although the underlying bytes are immutatable, the PDXInstance has a ByteSource
with a position field that changes. That means two threads doing serialization
or calling toString on the PdxInstance could result in one or more threads
getting a corrupt read.
It looks like they are ending up with the same instance because of the behavior
in LocalRegion.optimizedGetObject. We use futures to make sure there is only 1
get that goes through, and both threads receive the same value.
Ending up in optimizedGetObject requires a race with the put, because if the
value was in the cache at the beginning of the get it would be returned earlier
in the get process.
I put a test that reproduces this issue here -
https://github.com/upthewaterspout/geode/pull/new/feature/pdx-instances-shared
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