Question:

An error occurs when Webflux uploads a file:

14:32:24.628 [61667d78915db10adaa025b4da32871f/daa025b4da32871f] [reactor-http-epoll-4] ERROR o.s.w.s.a.HttpWebHandlerAdapter - [7161d1a8-33] 500 Server Error for HTTP POST "/api/XXXXX/XXXXX"
org.springframework.core.io.buffer.DataBufferLimitException: Part headers exceeded the memory usage limit of 8192 bytes
        at org.springframework.http.codec.multipart.MultipartParser$HeadersState.onNext(MultipartParser.java:360)
        Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException:
Error has been observed at the following site(s):
        |_ checkpoint ⇢ org.springframework.security.web.server.authentication.logout.LogoutWebFilter [DefaultWebFilterChain]
        |_ checkpoint ⇢ org.springframework.security.web.server.savedrequest.ServerRequestCacheWebFilter [DefaultWebFilterChain]
        |_ checkpoint ⇢ org.springframework.security.web.server.context.SecurityContextServerWebExchangeWebFilter [DefaultWebFilterChain]
        |_ checkpoint ⇢ org.springframework.security.web.server.authentication.AuthenticationWebFilter [DefaultWebFilterChain]
        |_ checkpoint ⇢ org.springframework.security.web.server.authentication.AuthenticationWebFilter [DefaultWebFilterChain]
        |_ checkpoint ⇢ org.springframework.security.web.server.context.ReactorContextWebFilter [DefaultWebFilterChain]
        |_ checkpoint ⇢ org.springframework.security.web.server.header.HttpHeaderWriterWebFilter [DefaultWebFilterChain]
        |_ checkpoint ⇢ org.springframework.security.config.web.server.ServerHttpSecurity$ServerWebExchangeReactorContextWebFilter [DefaultWebFilterChain]
        |_ checkpoint ⇢ org.springframework.security.web.server.WebFilterChainProxy [DefaultWebFilterChain]
        |_ checkpoint ⇢ org.springframework.cloud.sleuth.instrument.web.TraceWebFilter [DefaultWebFilterChain]
        |_ checkpoint ⇢ org.springframework.boot.actuate.metrics.web.reactive.server.MetricsWebFilter [DefaultWebFilterChain]
        |_ checkpoint ⇢ HTTP POST "/api/iot/notice/add" [ExceptionHandlingWebHandler]
Stack trace:
                at org.springframework.http.codec.multipart.MultipartParser$HeadersState.onNext(MultipartParser.java:360)
                at org.springframework.http.codec.multipart.MultipartParser.hookOnNext(MultipartParser.java:104)
                at org.springframework.http.codec.multipart.MultipartParser.hookOnNext(MultipartParser.java:46)
                at reactor.core.publisher.BaseSubscriber.onNext(BaseSubscriber.java:160)
                at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onNext(ScopePassingSpanSubscriber.java:90)
                at reactor.core.publisher.FluxMap$MapSubscriber.onNext(FluxMap.java:120)
                at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onNext(ScopePassingSpanSubscriber.java:90)
                at reactor.core.publisher.FluxPeek$PeekSubscriber.onNext(FluxPeek.java:199)
                at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onNext(ScopePassingSpanSubscriber.java:90)
                at reactor.core.publisher.FluxMap$MapSubscriber.onNext(FluxMap.java:120)
                at reactor.netty.channel.FluxReceive.drainReceiver(FluxReceive.java:265)
                at reactor.netty.channel.FluxReceive.onInboundNext(FluxReceive.java:371)
                at reactor.netty.channel.ChannelOperations.onInboundNext(ChannelOperations.java:381)
                at reactor.netty.http.server.HttpServerOperations.onInboundNext(HttpServerOperations.java:535)
                at reactor.netty.channel.ChannelOperationsHandler.channelRead(ChannelOperationsHandler.java:94)
                at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
                at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
                at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
                at reactor.netty.http.server.HttpTrafficHandler.channelRead(HttpTrafficHandler.java:252)
                at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
                at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
                at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
                at io.netty.channel.CombinedChannelDuplexHandler$DelegatingChannelHandlerContext.fireChannelRead(CombinedChannelDuplexHandler.java:436)
                at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:324)
                at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:311)
                at io.netty.handler.codec.ByteToMessageDecoder.callDecode(ByteToMessageDecoder.java:432)
                at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:276)
                at io.netty.channel.CombinedChannelDuplexHandler.channelRead(CombinedChannelDuplexHandler.java:251)
                at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
                at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
                at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
                at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410)
                at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
                at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
                at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919)
                at io.netty.channel.epoll.AbstractEpollStreamChannel$EpollStreamUnsafe.epollInReady(AbstractEpollStreamChannel.java:795)
                at io.netty.channel.epoll.AbstractEpollChannel$AbstractEpollUnsafe$1.run(AbstractEpollChannel.java:388)
                at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:164)
                at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:472)
                at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:384)
                at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989)
                at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
                at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
                at java.lang.Thread.run(Thread.java:882)

reason:

You can only upload files with a maximum size of 8KB, which exceeds the limit and cannot be uploaded normally

Solution:

Method I (not effective):

Direct setting    max-in-memory-size   It can take effect

spring:
  codec:
    max-in-memory-size: 100MB

However, the above code does not take effect in the spring 2.X.x version. The official said it was solved. It is estimated that it was solved in the later version, but the project has been produced. It is certainly impossible to change the version now, so we have to find another way. During his startup, debug found that it was set to 262144 when initializing the code:

Method II:

Configure configuration. In the configuration class of webfluxconfigurer in implements, implement configurehttpmessagecodes for configuration. The example is as follows

import org.springframework.context.annotation.Configuration;
import org.springframework.http.codec.ServerCodecConfigurer;
import org.springframework.http.codec.multipart.DefaultPartHttpMessageReader;
import org.springframework.http.codec.multipart.MultipartHttpMessageReader;
import org.springframework.web.reactive.config.WebFluxConfigurer;

@Configuration
public class WebConfig implements WebFluxConfigurer {

    @Override
    public void configureHttpMessageCodecs(ServerCodecConfigurer configurer) {
        DefaultPartHttpMessageReader partReader = new DefaultPartHttpMessageReader();
        // 9 KiB, default is 8 KiB
        partReader.setMaxHeadersSize(100*1024*1024);
        partReader.setEnableLoggingRequestDetails(true);

        MultipartHttpMessageReader multipartReader = new MultipartHttpMessageReader(partReader);
        multipartReader.setEnableLoggingRequestDetails(true);

        configurer.defaultCodecs().multipartReader(multipartReader);

    }
}

Done!