* improve large file sync throughput for remote.cache and filer.sync
Three main throughput improvements:
1. Adaptive chunk sizing for remote.cache: targets ~32 chunks per file
instead of always starting at 5MB. A 500MB file now uses ~16MB chunks
(32 chunks) instead of 5MB chunks (100 chunks), reducing per-chunk
overhead (volume assign, gRPC call, needle write) by 3x.
2. Configurable concurrency at every layer:
- remote.cache chunk concurrency: -chunkConcurrency flag (default 8)
- remote.cache S3 download concurrency: -downloadConcurrency flag
(default raised from 1 to 5 per chunk)
- filer.sync chunk concurrency: -chunkConcurrency flag (default 32)
3. S3 multipart download concurrency raised from 1 to 5: the S3 manager
downloader was using Concurrency=1, serializing all part downloads
within each chunk. This alone can 5x per-chunk download speed.
The concurrency values flow through the gRPC request chain:
shell command → CacheRemoteObjectToLocalClusterRequest →
FetchAndWriteNeedleRequest → S3 downloader
Zero values in the request mean "use server defaults", maintaining
full backward compatibility with existing callers.
Ref #8481
* fix: use full maxMB for chunk size cap and remove loop guard
Address review feedback:
- Use full maxMB instead of maxMB/2 for maxChunkSize to avoid
unnecessarily limiting chunk size for very large files.
- Remove chunkSize < maxChunkSize guard from the safety loop so it
can always grow past maxChunkSize when needed to stay under 1000
chunks (e.g., extremely large files with small maxMB).
* address review feedback: help text, validation, naming, docs
- Fix help text for -chunkConcurrency and -downloadConcurrency flags
to say "0 = server default" instead of advertising specific numeric
defaults that could drift from the server implementation.
- Validate chunkConcurrency and downloadConcurrency are within int32
range before narrowing, returning a user-facing error if out of range.
- Rename ReadRemoteErr to readRemoteErr to follow Go naming conventions.
- Add doc comment to SetChunkConcurrency noting it must be called
during initialization before replication goroutines start.
- Replace doubling loop in chunk size safety check with direct
ceil(remoteSize/1000) computation to guarantee the 1000-chunk cap.
* address Copilot review: clamp concurrency, fix chunk count, clarify proto docs
- Use ceiling division for chunk count check to avoid overcounting
when file size is an exact multiple of chunk size.
- Clamp chunkConcurrency (max 1024) and downloadConcurrency (max 1024
at filer, max 64 at volume server) to prevent excessive goroutines.
- Always use ReadFileWithConcurrency when the client supports it,
falling back to the implementation's default when value is 0.
- Clarify proto comments that download_concurrency only applies when
the remote storage client supports it (currently S3).
- Include specific server defaults in help text (e.g., "0 = server
default 8") so users see the actual values in -h output.
* fix data race on executionErr and use %w for error wrapping
- Protect concurrent writes to executionErr in remote.cache worker
goroutines with a sync.Mutex to eliminate the data race.
- Use %w instead of %v in volume_grpc_remote.go error formatting
to preserve the error chain for errors.Is/errors.As callers.
Chris Lu