Resize block buffer after allocation if significant wasted space #1674
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What does this PR do?
When constructing a block cache, the cache pre-allocates a buffer of max block size for each block. Payload generators then serialize bytes into that buffer. The buffer previously was never resized and thus held onto its excess memory. This made caches with small blocks hold (# blocks * max block size) in memory instead of the specified cache size.
This change resizes blocks that use under half of the pre-allocated space. This should enforce that the buffers of a cache are now no more than 2x the maximum configured cache size.
Motivation
Significant memory usage from my payload generator that has lots of smaller blocks.
Additional notes
We could probably resize every block since this is only done on lading creation anyways - wdyt? 2x was an arbitrary decision here.