Benedict created CASSANDRA-15229:
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Summary: BufferPool Regression
Key: CASSANDRA-15229
URL: https://issues.apache.org/jira/browse/CASSANDRA-15229
Project: Cassandra
Issue Type: Bug
Reporter: Benedict
The BufferPool was never intended to be used for a {{ChunkCache}}, and we need
to either change our behaviour to handle uncorrelated lifetimes or use
something else. This is particularly important with the default chunk size for
compressed sstables being reduced. If we address the problem, we should also
utilise the BufferPool for native transport connections like we do for
internode messaging, and reduce the number of pooling solutions we employ.
Probably the best thing to do is to improve BufferPool’s behaviour when used
for things with uncorrelated lifetimes, which essentially boils down to
tracking those chunks that have not been freed and re-circulating them when we
run out of completely free blocks. We should probably also permit
instantiating separate {{BufferPool}}, so that we can insulate internode
messaging from the {{ChunkCache}}, or at least have separate memory bounds for
each, and only share fully-freed chunks.
With these improvements we can also safely increase the {{BufferPool}} chunk
size to 128KiB or 256KiB, to guarantee we can fit compressed pages and reduce
the amount of global coordination and per-allocation overhead. We don’t need
1KiB granularity for allocations, nor 16 byte granularity for tiny allocations.
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