feat: add router_rebuild_min_interval to reduce CPU spikes from frequ…

apisix/cli/config.lua

@@ -49,7 +49,8 @@ local _M = {
     normalize_uri_like_servlet = false,
     router = {
       http = "radixtree_host_uri",
-      ssl = "radixtree_sni"
+      ssl = "radixtree_sni",
+      router_rebuild_min_interval = 0,
     },
     proxy_mode = "http",
     resolver_timeout = 5,

apisix/http/router/radixtree_host_uri.lua

@@ -20,13 +20,15 @@ local core = require("apisix.core")
 local event = require("apisix.core.event")
 local get_services = require("apisix.http.service").services
 local service_fetch = require("apisix.http.service").get
+local ngx_now = ngx.now
 local ipairs = ipairs
 local type = type
 local tab_insert = table.insert
 local loadstring = loadstring
 local pairs = pairs
 local cached_router_version
 local cached_service_version
+local last_router_rebuild_time
 local host_router
 local only_uri_router
 
@@ -148,11 +150,23 @@ function _M.match(api_ctx)
     if not cached_router_version or cached_router_version ~= user_routes.conf_version
         or not cached_service_version or cached_service_version ~= service_version
     then
+        local min_interval = _M.router_rebuild_min_interval or 0
+        if min_interval > 0 and last_router_rebuild_time then
+            local elapsed = ngx_now() - last_router_rebuild_time
+            if elapsed < min_interval then
+                core.log.info("skip router rebuild, elapsed: ", elapsed,
+                              "s, min_interval: ", min_interval, "s")
+                goto MATCH
+            end
+        end
+
         create_radixtree_router(user_routes.values)
         cached_router_version = user_routes.conf_version
         cached_service_version = service_version
+        last_router_rebuild_time = ngx_now()
     end
 
+    ::MATCH::
     return _M.matching(api_ctx)
 end
 

apisix/http/router/radixtree_uri.lua

@@ -18,8 +18,10 @@ local require = require
 local core = require("apisix.core")
 local base_router = require("apisix.http.route")
 local get_services = require("apisix.http.service").services
+local ngx_now = ngx.now
 local cached_router_version
 local cached_service_version
+local last_router_rebuild_time
 
 
 local _M = {version = 0.2}
@@ -33,12 +35,24 @@ function _M.match(api_ctx)
     if not cached_router_version or cached_router_version ~= user_routes.conf_version
         or not cached_service_version or cached_service_version ~= service_version
     then
+        local min_interval = _M.router_rebuild_min_interval or 0
+        if min_interval > 0 and last_router_rebuild_time then
+            local elapsed = ngx_now() - last_router_rebuild_time
+            if elapsed < min_interval then
+                core.log.info("skip router rebuild, elapsed: ", elapsed,
+                              "s, min_interval: ", min_interval, "s")
+                goto MATCH
+            end
+        end
+
         uri_router = base_router.create_radixtree_uri_router(user_routes.values,
                                                              uri_routes, false)
         cached_router_version = user_routes.conf_version
         cached_service_version = service_version
+        last_router_rebuild_time = ngx_now()
     end
 
+    ::MATCH::
     if not uri_router then
         core.log.error("failed to fetch valid `uri` router: ")
         return true

apisix/http/router/radixtree_uri_with_parameter.lua

@@ -18,8 +18,10 @@ local require = require
 local core = require("apisix.core")
 local base_router = require("apisix.http.route")
 local get_services = require("apisix.http.service").services
+local ngx_now = ngx.now
 local cached_router_version
 local cached_service_version
+local last_router_rebuild_time
 
 
 local _M = {}
@@ -33,12 +35,24 @@ function _M.match(api_ctx)
     if not cached_router_version or cached_router_version ~= user_routes.conf_version
         or not cached_service_version or cached_service_version ~= service_version
     then
+        local min_interval = _M.router_rebuild_min_interval or 0
+        if min_interval > 0 and last_router_rebuild_time then
+            local elapsed = ngx_now() - last_router_rebuild_time
+            if elapsed < min_interval then
+                core.log.info("skip router rebuild, elapsed: ", elapsed,
+                              "s, min_interval: ", min_interval, "s")
+                goto MATCH
+            end
+        end
+
         uri_router = base_router.create_radixtree_uri_router(user_routes.values,
                                                              uri_routes, true)
         cached_router_version = user_routes.conf_version
         cached_service_version = service_version
+        last_router_rebuild_time = ngx_now()
     end
 
+    ::MATCH::
     if not uri_router then
         core.log.error("failed to fetch valid `uri_with_parameter` router: ")
         return true

apisix/router.lua

@@ -23,6 +23,7 @@ local str_lower = string.lower
 local ipairs  = ipairs
 
 local _M = {version = 0.3}
+local router_rebuild_min_interval = 0
 
 
 local function filter(route)
@@ -76,11 +77,14 @@ function _M.http_init_worker()
     if conf and conf.apisix and conf.apisix.router then
         router_http_name = conf.apisix.router.http or router_http_name
         router_ssl_name = conf.apisix.router.ssl or router_ssl_name
+        router_rebuild_min_interval = conf.apisix.router.router_rebuild_min_interval
+                                      or router_rebuild_min_interval
     end
 
     local router_http = require("apisix.http.router." .. router_http_name)
     attach_http_router_common_methods(router_http)
     router_http.init_worker(filter)
+    router_http.router_rebuild_min_interval = router_rebuild_min_interval
     _M.router_http = router_http
 
     local router_ssl = require("apisix.ssl.router." .. router_ssl_name)
@@ -92,6 +96,7 @@ function _M.http_init_worker()
     if conf and conf.apisix and conf.apisix.stream_proxy then
         local router_stream = require("apisix.stream.router.ip_port")
         router_stream.stream_init_worker(filter)
+        router_stream.router_rebuild_min_interval = router_rebuild_min_interval
         _M.router_stream = router_stream
     end
 
@@ -100,10 +105,17 @@ end
 
 
 function _M.stream_init_worker()
+    local conf = core.config.local_conf()
     local router_ssl_name = "radixtree_sni"
+    local min_interval = 0
+
+    if conf and conf.apisix and conf.apisix.router then
+        min_interval = conf.apisix.router.router_rebuild_min_interval or 0
+    end
 
     local router_stream = require("apisix.stream.router.ip_port")
     router_stream.stream_init_worker(filter)
+    router_stream.router_rebuild_min_interval = min_interval
     _M.router_stream = router_stream
 
     local router_ssl = require("apisix.ssl.router." .. router_ssl_name)

apisix/stream/router/ip_port.lua

@@ -21,12 +21,14 @@ local stream_plugin_checker = require("apisix.plugin").stream_plugin_checker
 local router_new = require("apisix.utils.router").new
 local apisix_ssl = require("apisix.ssl")
 local xrpc = require("apisix.stream.xrpc")
+local ngx_now   = ngx.now
 local error     = error
 local tonumber  = tonumber
 local ipairs = ipairs
 
 local user_routes
 local router_ver
+local last_router_rebuild_time
 local tls_router
 local other_routes = {}
 local _M = {version = 0.1}
@@ -144,14 +146,27 @@ do
 
     function _M.match(api_ctx)
         if router_ver ~= user_routes.conf_version then
+            local min_interval = _M.router_rebuild_min_interval or 0
+            if min_interval > 0 and last_router_rebuild_time then
+                local elapsed = ngx_now() - last_router_rebuild_time
+                if elapsed < min_interval then
+                    core.log.info("skip stream router rebuild, elapsed: ", elapsed,
+                                  "s, min_interval: ", min_interval, "s")
+                    goto MATCH
+                end
+            end
+
             local err = create_router(user_routes.values)
             if err then
                 return false, "failed to create router: " .. err
             end
 
             router_ver = user_routes.conf_version
+            last_router_rebuild_time = ngx_now()
         end
 
+        ::MATCH::
+
         local sni = apisix_ssl.server_name()
         if sni and tls_router then
             local sni_rev = sni:reverse()

conf/config.yaml.example

@@ -71,6 +71,12 @@ apisix:
                                 # radixtree_uri: match route by URI
                                 # radixtree_uri_with_parameter: similar to radixtree_uri but match URI with parameters. See https://github.com/api7/lua-resty-radixtree/#parameters-in-path for more details.
     ssl: radixtree_sni          # radixtree_sni: match route by SNI
+    # router_rebuild_min_interval: 0  # Minimum interval (in seconds) between router rebuilds.
+                                      # When routes change frequently, the router is rebuilt on every
+                                      # change which can cause CPU spikes under high-frequency updates.
+                                      # Set this to a positive value (e.g. 1 or 5) to limit the
+                                      # rebuild frequency. Default 0 means rebuild immediately on
+                                      # every change (current behavior).
 
   # http is the default proxy mode. proxy_mode can be one of `http`, `stream`, or `http&stream`
   proxy_mode: "http"