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Update unstable log shrinking #462

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Update unstable log shrinking #462

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11 changes: 3 additions & 8 deletions log_unstable.go
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Original file line number Diff line number Diff line change
Expand Up @@ -168,17 +168,12 @@ func (u *unstable) stableTo(id entryID) {
// potentially large entries that aren't needed anymore. Simply clearing the
// entries wouldn't be safe because clients might still be using them.
func (u *unstable) shrinkEntriesArray() {
// We replace the array if we're using less than half of the space in
// it. This number is fairly arbitrary, chosen as an attempt to balance
// memory usage vs number of allocations. It could probably be improved
// with some focused tuning.
// TODO: revisit shrinking. Using len/cap wasn't useful since
// stableTo slices the entries. It might be better to shrink
// based on the actual size of the retained entries instead.
const lenMultiple = 2
Comment on lines +171 to 174

@ahrtr ahrtr Jul 6, 2026

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We don't have plan to spend too much effort to optimize this. Let's just keep it as simple as possible.

Suggested change
// TODO: revisit shrinking. Using len/cap wasn't useful since
// stableTo slices the entries. It might be better to shrink
// based on the actual size of the retained entries instead.
const lenMultiple = 2

if len(u.entries) == 0 {
u.entries = nil
} else if len(u.entries)*lenMultiple < cap(u.entries) {
newEntries := make([]*pb.Entry, len(u.entries))
copy(newEntries, u.entries)
u.entries = newEntries
}
}

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