Because multipart transfers can need more than one buffer to complete,
if transfers was set very high, it was possible for lots of multipart
transfers to start, grab fewer buffers than chunk size, then deadlock
because no more memory was available.
This fixes the problem by introducing a reservation system which the
multipart transfer uses to ensure it can reserve all the memory for
one chunk before starting.
This commit modernizes Go usage. This was done with:
go run golang.org/x/tools/gopls/internal/analysis/modernize/cmd/modernize@latest -fix -test ./...
Then files needed to be `go fmt`ed and a few comments needed to be
restored.
The modernizations include replacing
- if/else conditional assignment by a call to the built-in min or max functions added in go1.21
- sort.Slice(x, func(i, j int) bool) { return s[i] < s[j] } by a call to slices.Sort(s), added in go1.21
- interface{} by the 'any' type added in go1.18
- append([]T(nil), s...) by slices.Clone(s) or slices.Concat(s), added in go1.21
- loop around an m[k]=v map update by a call to one of the Collect, Copy, Clone, or Insert functions from the maps package, added in go1.21
- []byte(fmt.Sprintf...) by fmt.Appendf(nil, ...), added in go1.19
- append(s[:i], s[i+1]...) by slices.Delete(s, i, i+1), added in go1.21
- a 3-clause for i := 0; i < n; i++ {} loop by for i := range n {}, added in go1.22
Before this change the concurrency used for an upload was rather
inconsistent.
- if size below `--backend-upload-cutoff` (default 200M) do single part upload.
- if size below `--multi-thread-cutoff` (default 256M) or using streaming
uploads (eg `rclone rcat) do multipart upload using
`--backend-upload-concurrency` to set the concurrency used by the uploader.
- otherwise do multipart upload using `--multi-thread-streams` to set the
concurrency.
This change makes the default for the concurrency used be the
`--backend-upload-concurrency`. If `--multi-thread-streams` is set and larger
than the `--backend-upload-concurrency` then that will be used instead.
This means that if the user sets `--backend-upload-concurrency` then it will be
obeyed for all multipart/multi-thread transfers and the user can override them
all with `--multi-thread-streams`.
See: #7056
This makes the memory controls of the s3 backend inoperative and
replaced with the global ones.
--s3-memory-pool-flush-time
--s3-memory-pool-use-mmap
By using the buffered reader this fixes excessive memory use when
uploading large files as it will share memory pages between all
readers.
Fixes#7141
