membphis opened a new pull request, #13073:
URL: https://github.com/apache/apisix/pull/13073
## Description
When routes change frequently (e.g., 20-50 changes/sec with 5000+ total
routes), the data plane rebuilds the radixtree router on **every single
change**, causing significant CPU spikes (up to 80%) and temporary TPS drops.
This PR adds a configurable `router_rebuild_min_interval` option that sets a
minimum time interval (in seconds) between HTTP router rebuilds. When the
interval has not elapsed since the last rebuild, subsequent route changes are
acknowledged but the router rebuild is deferred, dramatically reducing CPU
usage during bulk route updates.
### Configuration
```yaml
apisix:
router:
http: radixtree_host_uri
ssl: radixtree_sni
router_rebuild_min_interval: 0 # default: 0 (rebuild immediately,
current behavior)
```
### Expected Impact
| Scenario (30s duration) | min_interval: 0 | min_interval: 1 |
min_interval: 5 |
|---|---|---|---|
| 20 changes/sec | 600 rebuilds | ~31 rebuilds | ~7 rebuilds |
| 50 changes/sec | 1500 rebuilds | ~31 rebuilds | ~7 rebuilds |
| 1 change/3sec | 10 rebuilds | 10 rebuilds | 10 rebuilds |
### Changes
- **`conf/config.yaml.example`**: Added `router_rebuild_min_interval` config
option
- **`apisix/cli/config.lua`**: Default value `0`
- **`apisix/router.lua`**: Reads config and passes to HTTP router modules
(+3 lines)
- **`apisix/http/router/radixtree_uri.lua`**: Min interval check before
rebuild
- **`apisix/http/router/radixtree_host_uri.lua`**: Min interval check before
rebuild
- **`apisix/http/router/radixtree_uri_with_parameter.lua`**: Min interval
check before rebuild
- **`t/router/router-rebuild-min-interval.t`**: Test cases covering default
behavior, skip behavior, and deferred rebuild
### Backward Compatibility
Default value is `0`, preserving the existing behavior of rebuilding
immediately on every route change. No existing configurations are affected.
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