ByteBuffer is not released when compression is enabled, causing pool leakage

[kulabun]

Hey Mongo team.

My team experienced an increased number of failures caused by latency recently. Further investigation showed that InternalStreamConnection doesn't close buffers returned by PowerOfTwoBufferPool when compression is enabled. It leads to permits leakage. After INTEGER_MAX buffer retrievals buffer pool is fully exhausted and all following requests would be blocked indefinitely unless the thread gets interrupted.

JAVA-4510

[kulabun]

An alternative way to address the issue can be buffer release as part of Compressor.ByteBufInputStream.close() method. For example, SocketInputStream works this way and closes the underlying socket as part of close call. But I think it's better to be explicit and close it within the same section that used it.

[stIncMale]

Hi @kulabun,

Thank you for the PR. I looked through the class InternalStreamConnection trying to see whether there are other places where we may not release buffers, and pushed a new commit.

Using your code from JAVA-4510 I confirmed that after the changes threads are not blocked due to ConcurrentPool.maxSize being exhausted. This can be done quickly by changing the ConcurrentPool.INFINITE_SIZE constant from Integer.MAX_VALUE to something small.

[jyemin]

Added a comment.

[jyemin]

LGTM