Optimize object creation in RequestMappingHandlerMapping#handleNoMatch

[koo-taejin]

related issue: #29611

RequestMappingInfoHandlerMapping handleNoMatch() method has the following format.
https://github.com/spring-projects/spring-framework/blob/main/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/RequestMappingInfoHandlerMapping.java#L246
https://github.com/spring-projects/spring-framework/blob/main/spring-webflux/src/main/java/org/springframework/web/reactive/result/method/RequestMappingInfoHandlerMapping.java#L169

@Override protected HandlerMethod handleNoMatch(Set<RequestMappingInfo> infos, ...) throws Exception {	PartialMatchHelper helper = new PartialMatchHelper(infos, exchange);	if (helper.isEmpty()) {	return null;	} ... } 

And this method may allow an empty value in Set<RequestMappingInfo> infos parameter.
(Unfortunately, it happens a lot in the service I am running.)

The constructor code of org.springframework.web.reactive.result.method.RequestMappingInfoHandlerMapping.PartialMatchHelper is shown below.
https://github.com/spring-projects/spring-framework/blob/main/spring-webflux/src/main/java/org/springframework/web/reactive/result/method/RequestMappingInfoHandlerMapping.java#L227

public PartialMatchHelper(Set<RequestMappingInfo> infos, ServerWebExchange exchange) {	this.partialMatches.addAll(infos.stream().	filter(info -> info.getPatternsCondition().getMatchingCondition(exchange) != null).	map(info -> new PartialMatch(info, exchange)).	collect(Collectors.toList())); } 

This code executes follwoing method even if there is no value in infos
java.util.Collection#stream
java.util.stream.Collectors#toList
java.util.stream.ReferencePipeline#collect(java.util.stream.Collector<? super P_OUT,A,R>)
Unnecessary resources are used via these methods.(create objects and execute operations, so )

Even though parameters have values, it seems better not to use Stream.

It can save resources by changing the constructor like mvc's RequestMappingInfoHandlerMapping.
https://github.com/spring-projects/spring-framework/blob/main/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/RequestMappingInfoHandlerMapping.java#L300

public PartialMatchHelper(Set<RequestMappingInfo> infos, HttpServletRequest request) {	for (RequestMappingInfo info : infos) {	if (info.getActivePatternsCondition().getMatchingCondition(request) != null) {	this.partialMatches.add(new PartialMatch(info, request));	}	}	} 

Below is a test created similar to the code above.

1. style of webflux
2. style of mvc
3. style of reuse object

• test code

public class PartialMatchHelperTest { @Test public void partialMatchHelperTest() { int count = 1000 * 1000 * 100; ThreadMXBean mxBean = ManagementFactory.getThreadMXBean(); // 1) long startTime = System.currentTimeMillis(); final long startCpuTime = mxBean.getCurrentThreadCpuTime(); for (int i = 0; i < count; i++) { new PartialMatchHelper(Collections.emptySet()); } System.out.println(System.currentTimeMillis() - startTime); System.out.println(mxBean.getCurrentThreadCpuTime() - startCpuTime); // 2) long startTime2 = System.currentTimeMillis(); final long startCpuTime2 = mxBean.getCurrentThreadCpuTime(); for (int i = 0; i < count; i++) { new PartialMatchHelper2(Collections.emptySet()); } System.out.println(System.currentTimeMillis() - startTime2); System.out.println(mxBean.getCurrentThreadCpuTime() - startCpuTime2); // 3) long startTime3 = System.currentTimeMillis(); final long startCpuTime3 = mxBean.getCurrentThreadCpuTime(); for (int i = 0; i < count; i++) { PartialMatchHelper3.of(Collections.emptySet()); } System.out.println(System.currentTimeMillis() - startTime3); System.out.println(mxBean.getCurrentThreadCpuTime() - startCpuTime3); } private static class PartialMatchHelper { private final List<PartialMatch> partialMatches = new ArrayList<>(); public PartialMatchHelper(Set<RequestMappingInfo> infos) { partialMatches.addAll(infos.stream(). filter(info -> info.getPatternsCondition().getMatchingCondition(null) != null). map(info -> new PartialMatch(info)). collect(Collectors.toList())); } public boolean isEmpty() { return partialMatches.isEmpty(); } } private class PartialMatchHelper2 { private final List<PartialMatch> partialMatches = new ArrayList<>(); public PartialMatchHelper2(Set<RequestMappingInfo> infos) { for (RequestMappingInfo info : infos) { if (info.getMatchingCondition(null) != null) { this.partialMatches.add(new PartialMatch(info)); } } } public boolean isEmpty() { return partialMatches.isEmpty(); } } private static class PartialMatchHelper3 { static PartialMatchHelper3 DISALBELD = new PartialMatchHelper3(Collections.emptySet()); private final List<PartialMatch> partialMatches = new ArrayList<>(); public static PartialMatchHelper3 of(Set<RequestMappingInfo> infos) { if (infos.isEmpty()) { return DISALBELD; } else { return new PartialMatchHelper3(infos); } } public PartialMatchHelper3(Set<RequestMappingInfo> infos) { for (RequestMappingInfo info : infos) { if (info.getMatchingCondition(null) != null) { this.partialMatches.add(new PartialMatch(info)); } } } public boolean isEmpty() { return partialMatches.isEmpty(); } } private static class PartialMatch { private final RequestMappingInfo info; public PartialMatch(RequestMappingInfo info) { this.info = info; } public RequestMappingInfo getInfo() { return this.info; } @Override public String toString() { return this.info.toString(); } } } 

Result (from Async Profiler)

 1) samples : CPU 393, Memory allocations 13,474,672 2) samples : CPU 580, Memory allocations 4,804,133,448 3) samples : CPU 6,547, Memory allocations 37,581,912,072 

In my opinion, the following order seems like a good way.
(Suggested solution (3 + 2) -> 3 -> 2 -> 1)

I will make PR according to your opinion.

Thanks :)

[koo-taejin]

I have worked for Only the initialization part mentioned in the issue.
The performance of Stream itself is not good, so it would be better if other parts were improved.
http://www.angelikalanger.com/Conferences/Videos/Conference-Video-GeeCon-2015-Performance-Model-of-Streams-in-Java-8-Angelika-Langer.html

If you want to change the other parts to the collector's loop as before.
Please let me know, then I am going to work for it.

Thanks :)

[rstoyanchev]

Backported to 5.3.25 with #29667.