Add ServerWebExchange a new attribute for PathContainer to avoid repeating parsePath in PathRoutePredicateFactory.

[LiRuihaoA]

What I DO

During lookupRoute, serverWebExchange add a new attribute for PathContainer to avoid repeating parsePath in PathRoutePredicateFactory. Thereby reducing cpu load and increasing throughput.

1. Background:

We have an Spring Cloud Gateway online service with about 2k path predicate routes;
And we found that Spring Cloud Gateway has high cpu load when pressure test request of a route.

2. Flame Graph and Cause

The CPU flame graph shows that the PathContainer.parsePath in PathRoutePredicateFactory consumes high cpu.

From the code, It is normal that the large number of routes leads to frequent execution of Predicate.apply.


But an exchange’s PathContainer is unchanged during the lookupRoute, there is no need to parsePath every time when test predicate.

PathRoutePredicateFactory's test method.

3. Change Details

So in PathRoutePredicateFactory, I hope exchange add a new attribute as below, to store its pathContainer.
When there are many path routes, only parsePath one time for a request.

Below is the cpu flame graph after the update.

4. BenchMark

The following is the benchmark result of PathRoutePredicateFactory‘s test method. Throughput has been significantly improved after adding the new attribute.

Result of Test method with new attribute.

Result of Test method without new attribute.

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[spencergibb]

Thanks for your first contribution! I polished things a bit here 5d8c2cf

[LiRuihaoA]

Hi Spencer, thanks for your code review! Glad to contribute~