shouldMergeChunks only counted non-manifest chunk sizes toward the bloat
threshold, so overlapping manifests accumulated undetected across flush
cycles.
During sustained random writes (e.g. fio), each metadata flush compacts
non-manifest chunks and may group them into a new manifest via
MaybeManifestize, while carrying forward all existing manifests. Since
the merge condition only checked non-manifest totals against 2x file
size, the growing pile of redundant manifests never triggered a merge.
In a real workload: 4 GB file, 25 manifests each covering ~4 GB
(107 GB manifest data on volume servers), but shouldMergeChunks saw only
4.2 GB of non-manifest chunks vs the 8.6 GB threshold -- no merge.
Fix: include manifest coverage sizes in totalChunkSize. This correctly
detects the 111 GB total vs 8.6 GB threshold and triggers the merge,
which re-reads the file as clean chunks and lets the filer's MinusChunks
(which resolves manifests) garbage-collect all redundant sub-chunks.
Chris Lu
4f1d3a1f84