* mount: improve read throughput with parallel chunk fetching
This addresses issue #7504 where a single weed mount FUSE instance
does not fully utilize node network bandwidth when reading large files.
Changes:
- Add -concurrentReaders mount option (default: 16) to control the
maximum number of parallel chunk fetches during read operations
- Implement parallel section reading in ChunkGroup.ReadDataAt() using
errgroup for better throughput when reading across multiple sections
- Enhance ReaderCache with MaybeCacheMany() to prefetch multiple chunks
ahead in parallel during sequential reads (now prefetches 4 chunks)
- Increase ReaderCache limit dynamically based on concurrentReaders
to support higher read parallelism
The bottleneck was that chunks were being read sequentially even when
they reside on different volume servers. By introducing parallel chunk
fetching, a single mount instance can now better saturate available
network bandwidth.
Fixes: #7504
* fmt
* Address review comments: make prefetch configurable, improve error handling
Changes:
1. Add DefaultPrefetchCount constant (4) to reader_at.go
2. Add GetPrefetchCount() method to ChunkGroup that derives prefetch count
from concurrentReaders (1/4 ratio, min 1, max 8)
3. Pass prefetch count through NewChunkReaderAtFromClient
4. Fix error handling in readDataAtParallel to prioritize errgroup error
5. Update all callers to use DefaultPrefetchCount constant
For mount operations, prefetch scales with -concurrentReaders:
- concurrentReaders=16 (default) -> prefetch=4
- concurrentReaders=32 -> prefetch=8 (capped)
- concurrentReaders=4 -> prefetch=1
For non-mount paths (WebDAV, query engine, MQ), uses DefaultPrefetchCount.
* fmt
* Refactor: use variadic parameter instead of new function name
Use NewChunkGroup with optional concurrentReaders parameter instead of
creating a separate NewChunkGroupWithConcurrency function.
This maintains backward compatibility - existing callers without the
parameter get the default of 16 concurrent readers.
* Use explicit concurrentReaders parameter instead of variadic
* Refactor: use MaybeCache with count parameter instead of new MaybeCacheMany function
* Address nitpick review comments
- Add upper bound (128) on concurrentReaders to prevent excessive goroutine fan-out
- Cap readerCacheLimit at 256 accordingly
- Fix SetChunks: use Lock() instead of RLock() since we are writing to group.sections
* compare chunks by timestamp
* fix slab clearing error
* fix test compilation
* move oldest chunk to sealed, instead of by fullness
* lock on fh.entryViewCache
* remove verbose logs
* revert slat clearing
* less logs
* less logs
* track write and read by timestamp
* remove useless logic
* add entry lock on file handle release
* use mem chunk only, swap file chunk has problems
* comment out code that maybe used later
* add debug mode to compare data read and write
* more efficient readResolvedChunks with linked list
* small optimization
* fix test compilation
* minor fix on writer
* add SeparateGarbageChunks
* group chunks into sections
* turn off debug mode
* fix tests
* fix tests
* tmp enable swap file chunk
* Revert "tmp enable swap file chunk"
This reverts commit 985137ec472924e4815f258189f6ca9f2168a0a7.
* simple refactoring
* simple refactoring
* do not re-use swap file chunk. Sealed chunks should not be re-used.
* comment out debugging facilities
* either mem chunk or swap file chunk is fine now
* remove orderedMutex as *semaphore.Weighted
not found impactful
* optimize size calculation for changing large files
* optimize performance to avoid going through the long list of chunks
* still problems with swap file chunk
* rename
* tiny optimization
* swap file chunk save only successfully read data
* fix
* enable both mem and swap file chunk
* resolve chunks with range
* rename
* fix chunk interval list
* also change file handle chunk group when adding chunks
* pick in-active chunk with time-decayed counter
* fix compilation
* avoid nil with empty fh.entry
* refactoring
* rename
* rename
* refactor visible intervals to *list.List
* refactor chunkViews to *list.List
* add IntervalList for generic interval list
* change visible interval to use IntervalList in generics
* cahnge chunkViews to *IntervalList[*ChunkView]
* use NewFileChunkSection to create
* rename variables
* refactor
* fix renaming leftover
* renaming
* renaming
* add insert interval
* interval list adds lock
* incrementally add chunks to readers
Fixes:
1. set start and stop offset for the value object
2. clone the value object
3. use pointer instead of copy-by-value when passing to interval.Value
4. use insert interval since adding chunk could be out of order
* fix tests compilation
* fix tests compilation
