环境
spring-cloud-gateway 版本
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-gateway</artifactId>
<version>2.1.2.RELEASE</version>
</dependency>
现象
监控发现某些请求响应时间特别长，查看链路追踪，发现请求触发了路由加载，由于使用自定义MySqlRouteDefinitionRepository从数据库里获取路由，导致了数据库负载特别高。
请求查找路由堆栈
org.springframework.web.reactive.handler.AbstractHandlerMapping#getHandler
org.springframework.cloud.gateway.handler.RoutePredicateHandlerMapping#getHandlerInternal
org.springframework.cloud.gateway.handler.RoutePredicateHandlerMapping#lookupRoute
org.springframework.cloud.gateway.route.CachingRouteLocator#getRoutes
org.springframework.cloud.gateway.route.CompositeRouteLocator#getRoutes
org.springframework.cloud.gateway.route.RouteDefinitionRouteLocator#getRoutes
org.springframework.cloud.gateway.route.CompositeRouteDefinitionLocator#getRouteDefinitions
由请求堆栈可以看到中间使用CachingRouteLocator对路由进行了缓存
CachingRouteLocator 源码
spring-cloud-gateway 2.1.2.RELEASE 版本
当收到RefreshRoutesEvent事件时，会调用refresh()方法清除缓存，导致了请求的时候也可能遇上缓存为空而导致触发加载路由。
由于当前项目使用了nacos，当发生心跳的时候会触发 RefreshRoutesEvent 导致清除缓存，刷新路由。细节可查看我之前的文章spring-cloud-gateway+nacos 每30s 加载路由一次
此时缓存清空了，刚好收到请求也会触发路由加载。
public class CachingRouteLocator
implements RouteLocator, ApplicationListener<RefreshRoutesEvent> {
private final RouteLocator delegate;
private final Flux<Route> routes;
private final Map<String, List> cache = new HashMap<>();
public CachingRouteLocator(RouteLocator delegate) {
this.delegate = delegate;
routes = CacheFlux.lookup(cache, "routes", Route.class)
.onCacheMissResume(() -> this.delegate.getRoutes()
.sort(AnnotationAwareOrderComparator.INSTANCE));
}
@Override
public Flux<Route> getRoutes() {
return this.routes;
}
/**
* Clears the routes cache.
* @return routes flux
*/
public Flux<Route> refresh() {
this.cache.clear();
return this.routes;
}
@Override
public void onApplicationEvent(RefreshRoutesEvent event) {
refresh();
}
@Deprecated
/* for testing */ void handleRefresh() {
refresh();
}
}
spring-cloud-gateway 4.0.7版本
可以看到收到RefreshRoutesEvent事件时，没有清除缓存，那么路由会直接从缓存中获取，不会触发路由加载。
package org.springframework.cloud.gateway.route;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.stream.Collectors;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import reactor.cache.CacheFlux;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;
import org.springframework.cloud.gateway.event.RefreshRoutesEvent;
import org.springframework.cloud.gateway.event.RefreshRoutesResultEvent;
import org.springframework.context.ApplicationEventPublisher;
import org.springframework.context.ApplicationEventPublisherAware;
import org.springframework.context.ApplicationListener;
import org.springframework.core.Ordered;
import org.springframework.core.annotation.AnnotationAwareOrderComparator;
/**
* @author Spencer Gibb
*/
public class CachingRouteLocator
implements Ordered, RouteLocator, ApplicationListener<RefreshRoutesEvent>, ApplicationEventPublisherAware {
private static final Log log = LogFactory.getLog(CachingRouteLocator.class);
private static final String CACHE_KEY = "routes";
private final RouteLocator delegate;
private final Flux<Route> routes;
private final Map<String, List> cache = new ConcurrentHashMap<>();
private ApplicationEventPublisher applicationEventPublisher;
public CachingRouteLocator(RouteLocator delegate) {
this.delegate = delegate;
routes = CacheFlux.lookup(cache, CACHE_KEY, Route.class).onCacheMissResume(this::fetch);
}
private Flux<Route> fetch() {
return this.delegate.getRoutes().sort(AnnotationAwareOrderComparator.INSTANCE);
}
private Flux<Route> fetch(Map<String, Object> metadata) {
return this.delegate.getRoutesByMetadata(metadata).sort(AnnotationAwareOrderComparator.INSTANCE);
}
@Override
public Flux<Route> getRoutes() {
return this.routes;
}
/**
* Clears the routes cache.
* @return routes flux
*/
public Flux<Route> refresh() {
this.cache.remove(CACHE_KEY);
return this.routes;
}
@Override
public void onApplicationEvent(RefreshRoutesEvent event) {
try {
if (this.cache.containsKey(CACHE_KEY) && event.isScoped()) {
final Mono<List<Route>> scopedRoutes = fetch(event.getMetadata()).collect(Collectors.toList())
.onErrorResume(s -> Mono.just(List.of()));
scopedRoutes.subscribe(scopedRoutesList -> {
Flux.concat(Flux.fromIterable(scopedRoutesList), getNonScopedRoutes(event)).materialize()
.collect(Collectors.toList()).subscribe(signals -> {
applicationEventPublisher.publishEvent(new RefreshRoutesResultEvent(this));
cache.put(CACHE_KEY, signals);
}, this::handleRefreshError);
}, this::handleRefreshError);
}
else {
final Mono<List<Route>> allRoutes = fetch().collect(Collectors.toList());
allRoutes.subscribe(list -> Flux.fromIterable(list).materialize().collect(Collectors.toList())
.subscribe(signals -> {
applicationEventPublisher.publishEvent(new RefreshRoutesResultEvent(this));
cache.put(CACHE_KEY, signals);
}, this::handleRefreshError), this::handleRefreshError);
}
}
catch (Throwable e) {
handleRefreshError(e);
}
}
private Flux<Route> getNonScopedRoutes(RefreshRoutesEvent scopedEvent) {
return this.getRoutes()
.filter(route -> !RouteLocator.matchMetadata(route.getMetadata(), scopedEvent.getMetadata()));
}
private void handleRefreshError(Throwable throwable) {
if (log.isErrorEnabled()) {
log.error("Refresh routes error !!!", throwable);
}
applicationEventPublisher.publishEvent(new RefreshRoutesResultEvent(this, throwable));
}
@Override
public int getOrder() {
return 0;
}
@Override
public void setApplicationEventPublisher(ApplicationEventPublisher applicationEventPublisher) {
this.applicationEventPublisher = applicationEventPublisher;
}
}
