This turned out to be a problem in the tests. The tests used to do
1. allocate
2. increment
3. free
4. decrement
But if one goroutine had just completed 2 and another had just
completed 3 then this can cause the test to register too many
allocations.
This was fixed by doing the test in this order instead:
1. allocate
2. increment
3. decrement
4. free
The 4 operations are atomic.
Fixes#8813
Before this change we used an overcomplicated method of memory
reservations in the pool.RW which caused deadlocks.
This changes it to use a much simpler reservation system where we
actually reserve the memory and store it in the pool.RW. This allows
us to use the semaphore.Weighted to count the actually memory in use
(rather than the memory in use and in the cache). This in turn allows
accurate use of the semaphore by users wanting memory.
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
This changes log statements from log to fs package, which is required for --use-json-log
to properly make log output in JSON format. The recently added custom linting rule,
handled by ruleguard via gocritic via golangci-lint, warns about these and suggests
the alternative. Fixing was therefore basically running "golangci-lint run --fix",
although some manual fixup of mainly imports are necessary following that.
