nic-6443 opened a new pull request, #13704: URL: https://github.com/apache/apisix/pull/13704
### Description `commit()` in the sliding-window limiter reports `limit - current_count` as the remaining quota, while `incoming()` reports the window-weighted value (`limit - current_count - last_count * remaining_time / window`). Delayed sync (`sync_interval`) flushes locally-permitted deltas through `commit()` and caches the reported remaining as the global quota for the next interval, so at every window boundary each gateway instance starts again from a nearly full budget: the sliding window effectively degrades into a per-window fixed window. The effect is easy to measure: 2 instances sharing one Redis, `count=500`, `time_window=1`, `window_type=sliding`, `sync_interval=0.2`, sustained 800 rps for 30s. Ideal admission is 500/s. Before this change the gateways admit ~590/s (+18% over the limit, bursty at each window start); with this change they admit ~438/s and converge, matching what the pre-#13443 flush path (which used `incoming()` for flushing) produced. The remaining gap below the limit is the inherent cost of the delayed-sync snapshot, not new behavior. The fix reads the previous window counter after the increment and reports the same weighted remaining as `incoming()`. A failed read must not fail the commit — the delta is already recorded, and the delayed syncer would retry and double-count it — so it degrades to the unweighted remaining and logs instead. The unconditional increment behavior from #13443 is unchanged: only the reported remaining is corrected. #### Which issue(s) this PR fixes: Introduced in #13443. ### Checklist - [x] I have explained the need for this PR and the problem it solves - [x] I have explained the changes or the new features added to this PR - [x] I have added tests corresponding to this change - [ ] I have updated the documentation to reflect this change (no documented behavior changes) - [x] I have verified that this change is backward compatible (If not, please discuss on the [APISIX mailing list](https://github.com/apache/apisix/tree/master#community) first) -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
