Daniel Norberg created CASSANDRA-4708:
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Summary: StorageProxy slow-down and memory leak
Key: CASSANDRA-4708
URL: https://issues.apache.org/jira/browse/CASSANDRA-4708
Project: Cassandra
Issue Type: Bug
Reporter: Daniel Norberg
I am consistently observing slow-downs in StorageProxy caused by the
NonBlockingHashMap used indirectly by MessagingService via the callbacks
ExpiringMap.
This seems do be due to NBHM having unbounded memory usage in the face of
workloads with high key churn. As monotonically increasing integers are used as
callback id's by MessagingService, the backing NBHM eventually ends up growing
the backing store unboundedly. This causes it to also do very large and
expensive backing store reallocation and migrations, causing throughput to drop
to tens of operations per second, lasting seconds or even minutes.
This behavior is especially noticable for high throughput workloads where the
dataset is completely in ram and I'm doing up to a hundred thousand reads per
second.
Replacing NBHM in ExpiringMap with the java standard library ConcurrentHashMap
resolved the issue and allowed me to keep a consistent high throughput.
An open issue on NBHM can be seen here:
http://sourceforge.net/tracker/?func=detail&aid=3563980&group_id=194172&atid=948362
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