Hi everyone,

In Spring Boot 2.2.5, one can choose their own json provider.

  1. Exclude the default Jackson
  2. Add the Yasson dependency in pom.xml (which also brings the JSON-B API + JSON-P). API versions are managed by the Parent pom.xml, nice! 
<dependency>
    <groupId>org.eclipse</groupId>
    <artifactId>yasson</artifactId>
    <version>1.0.6</version>
    <scope>runtime</scope>
</dependency>
  1. Specify in application.properties the following: spring.http.converters.preferred-json-mapper=jsonb

This setup seems to work like a charm, except the logs contain an error at each request:

2020-03-16 16:09:20.306 ERROR 1540 --- [io-8090-exec-10] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception

java.io.IOException: Stream closed
        at sun.nio.cs.StreamEncoder.ensureOpen(StreamEncoder.java:45) ~[na:1.8.0_202]
        at sun.nio.cs.StreamEncoder.flush(StreamEncoder.java:140) ~[na:1.8.0_202]
        at java.io.OutputStreamWriter.flush(OutputStreamWriter.java:229) ~[na:1.8.0_202]
        at org.springframework.http.converter.json.AbstractJsonHttpMessageConverter.writeInternal(AbstractJsonHttpMessageConverter.java:130) ~[spring-web-5.2.4.RELEASE.jar:5.2.4.RELEASE]
        at org.springframework.http.converter.AbstractGenericHttpMessageConverter.write(AbstractGenericHttpMessageConverter.java:104) ~[spring-web-5.2.4.RELEASE.jar:5.2.4.RELEASE]
        at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:287) ~[spring-webmvc-5.2.4.RELEASE.jar:5.2.4.RELEASE]
        at org.springframework.web.servlet.mvc.method.annotation.HttpEntityMethodProcessor.handleReturnValue(HttpEntityMethodProcessor.java:226) ~[spring-webmvc-5.2.4.RELEASE.jar:5.2.4.RELEASE]
        at org.springframework.web.method.support.HandlerMethodReturnValueHandlerComposite.handleReturnValue(HandlerMethodReturnValueHandlerComposite.java:82) ~[spring-web-5.2.4.RELEASE.jar:5.2.4.RELEASE]
        at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:124) ~[spring-webmvc-5.2.4.RELEASE.jar:5.2.4.RELEASE]
        at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:879) ~[spring-webmvc-5.2.4.RELEASE.jar:5.2.4.RELEASE]
        at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:793) ~[spring-webmvc-5.2.4.RELEASE.jar:5.2.4.RELEASE]
        at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.2.4.RELEASE.jar:5.2.4.RELEASE]
        at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040) ~[spring-webmvc-5.2.4.RELEASE.jar:5.2.4.RELEASE]
        at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943) ~[spring-webmvc-5.2.4.RELEASE.jar:5.2.4.RELEASE]
        at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.2.4.RELEASE.jar:5.2.4.RELEASE]
        at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.2.4.RELEASE.jar:5.2.4.RELEASE]
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:634) ~[tomcat-embed-core-9.0.31.jar:9.0.31]
        at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.2.4.RELEASE.jar:5.2.4.RELEASE]
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) ~[tomcat-embed-core-9.0.31.jar:9.0.31]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.31.jar:9.0.31]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.31.jar:9.0.31]
        at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.31.jar:9.0.31]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.31.jar:9.0.31]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.31.jar:9.0.31]
        at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.2.4.RELEASE.jar:5.2.4.RELEASE]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.4.RELEASE.jar:5.2.4.RELEASE]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.31.jar:9.0.31]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.31.jar:9.0.31]
        at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.2.4.RELEASE.jar:5.2.4.RELEASE]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.4.RELEASE.jar:5.2.4.RELEASE]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.31.jar:9.0.31]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.31.jar:9.0.31]
        at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.2.4.RELEASE.jar:5.2.4.RELEASE]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.4.RELEASE.jar:5.2.4.RELEASE]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.31.jar:9.0.31]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.31.jar:9.0.31]
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.31.jar:9.0.31]
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-9.0.31.jar:9.0.31]
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541) [tomcat-embed-core-9.0.31.jar:9.0.31]
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) [tomcat-embed-core-9.0.31.jar:9.0.31]
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.31.jar:9.0.31]
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) [tomcat-embed-core-9.0.31.jar:9.0.31]
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) [tomcat-embed-core-9.0.31.jar:9.0.31]
        at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:367) [tomcat-embed-core-9.0.31.jar:9.0.31]
        at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) [tomcat-embed-core-9.0.31.jar:9.0.31]
        at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868) [tomcat-embed-core-9.0.31.jar:9.0.31]
        at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1639) [tomcat-embed-core-9.0.31.jar:9.0.31]
        at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.31.jar:9.0.31]
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_202]
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_202]
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.31.jar:9.0.31]
        at java.lang.Thread.run(Thread.java:748) [na:1.8.0_202]

2020-03-16 16:09:20.354 ERROR 1540 --- [io-8090-exec-10] s.e.ErrorMvcAutoConfiguration$StaticView : Cannot render error page for request [/country] and exception [Stream closed] as the response has already been committed. As a result, the response may have the wrong status code.

Apparently more people are having the same issue. See here and here.

Any idea why this could happen? Do you think it's a bug in Yasson or in Spring Boot? I initially thought it's clearly a bug in SpringBoot (reading a Servlet Request stream twice, maybe?) but this doesn't happen with the default Jackson.

Any help would be greatly appreciated! I'd like to stick as close as possible to the Java Standards, and JSON-B is the actual standard for Json binding and processing...

EDIT: I updated the description to add the full stacktrace.

Comment From: amihaiemil

You can also follow the discussion in the Yasson repository: https://github.com/eclipse-ee4j/yasson/issues/389

This could apparently be fixed on both sides.

Comment From: wilkinsona

This looks like a bug in Yasson to me. Spring MVC's JSON HTTP message converter calls Jsonb.toJson(o, writer). There's no indication in the javadoc of toJson that it will close the writer, but it does.

You can reproduce this behaviour without Spring Boot:

FileWriter writer = new FileWriter("output.json");
Jsonb jsonb = JsonbBuilder.create();
jsonb.toJson(Collections.singletonMap("a", "alpha"), writer);
jsonb.toJson(Collections.singletonMap("a", "alpha"), writer);

Running the above will fail on the second call to toJson:

Exception in thread "main" javax.json.JsonException: I/O error while writing in JsonGenerator
    at org.glassfish.json.JsonGeneratorImpl.flushBuffer(JsonGeneratorImpl.java:635)
    at org.glassfish.json.JsonGeneratorImpl.close(JsonGeneratorImpl.java:513)
    at org.eclipse.yasson.internal.Marshaller.marshall(Marshaller.java:84)
    at org.eclipse.yasson.internal.Marshaller.marshall(Marshaller.java:100)
    at org.eclipse.yasson.internal.JsonBinding.toJson(JsonBinding.java:141)
    at com.example.demo.Gh20534Application.main(Gh20534Application.java:24)
Caused by: java.io.IOException: Stream closed
    at sun.nio.cs.StreamEncoder.ensureOpen(StreamEncoder.java:45)
    at sun.nio.cs.StreamEncoder.write(StreamEncoder.java:118)
    at java.io.OutputStreamWriter.write(OutputStreamWriter.java:207)
    at org.glassfish.json.JsonGeneratorImpl.flushBuffer(JsonGeneratorImpl.java:631)
    ... 5 more

I've just tried with Apache Johnzon and the problem does not occur. At this point, I'm convinced that this is a bug in Yasson.

With reference to the discussion on eclipse-ee4j/yasson#389, calling close() rather than flush() on the Spring side is not a viable option as the HTTP message converter has no way of knowing if anything after it will want to write to the same writer.