잭스의 SerializerCache에서 스레드가 막히는 경우

Question

이상한 행동을 발견했을 때 스프링 부트 1.3.5 애플리케이션을로드 테스트했습니다. 초당 요청 수를 5000으로 늘리면 스레드가 Jackson의 SerializerCache에서 차단되기 시작했습니다. 여기 JProfiler와는 나에게 말한다 무엇 년대 /status 엔드 포인트에서 동시 요청의 무리를 던지는시

@SpringBootApplication 
public class DojoRestApplication { 
    public static void main(String[] args) { 
    SpringApplication.run(DojoRestApplication.class, args); 
    } 

    @RestController 
    public static final class StatusController { 
    @RequestMapping(method = GET, path = "/status", produces = "application/json") 
    public ResponseEntity<ApplicationStatus> get() { 
     final ApplicationStatus result = new ApplicationStatus(); 
     result.setTimestamp(Instant.now()); 
     result.setVersion("1.0.0"); 
     return ResponseEntity.ok(result); 
    } 
    } 

    public static final class ApplicationStatus { 
    private Instant timestamp; 
    private String version; 

    public Instant getTimestamp() { 
     return timestamp; 
    } 

    public String getVersion() { 
     return version; 
    } 

    public void setTimestamp(Instant timestamp) { 
     this.timestamp = timestamp; 
    } 

    public void setVersion(String version) { 
     this.version = version; 
    } 
    } 
} 

: 처음에 나는 내 측면에서 잘못 될 수 있다고 생각, 그래서 나는 신선한, 최소한의 응용 프로그램을 만들었

나는 스레드 덤프를 가져다가 거의 모든 스레드가이에 붙어 :

com.fasterxml.jackson.databind.ser.SerializerCache.untypedValueSerializer(java.lang.Class) (line: 84) 
com.fasterxml.jackson.databind.SerializerProvider._findExplicitUntypedSerializer(java.lang.Class) (line: 1124) 
com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.hasSerializerFor(java.lang.Class, java.util.concurrent.atomic.AtomicReference) (line: 422) 
com.fasterxml.jackson.databind.ObjectMapper.canSerialize(java.lang.Class, java.util.concurrent.atomic.AtomicReference) 
org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.canWrite(java.lang.Class, org.springframework.http.MediaType) (line: 178) 
org.springframework.http.converter.AbstractGenericHttpMessageConverter.canWrite(java.lang.reflect.Type, java.lang.Class, org.springframework.http.MediaType) 
org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(java.lang.Object, org.springframework.core.MethodParameter, org.springframework.http.server.ServletServerHttpRequest, org.springframework.http.server.ServletServerHttpResponse) (line: 215) 
org.springframework.web.servlet.mvc.method.annotation.HttpEntityMethodProcessor.handleReturnValue(java.lang.Object, org.springframework.core.MethodParameter, org.springframework.web.method.support.ModelAndViewContainer, org.springframework.web.context.request.NativeWebRequest) (line: 183) 
org.springframework.web.method.support.HandlerMethodReturnValueHandlerComposite.handleReturnValue(java.lang.Object, org.springframework.core.MethodParameter, org.springframework.web.method.support.ModelAndViewContainer, org.springframework.web.context.request.NativeWebRequest) (line: 81) 
org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(org.springframework.web.context.request.ServletWebRequest, org.springframework.web.method.support.ModelAndViewContainer, java.lang.Object[ ]) (line: 126) 
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse, org.springframework.web.method.HandlerMethod) (line: 832) 
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse, org.springframework.web.method.HandlerMethod) (line: 743) 
org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse, java.lang.Object) 
org.springframework.web.servlet.DispatcherServlet.doDispatch(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse) (line: 961) 
org.springframework.web.servlet.DispatcherServlet.doService(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse) (line: 895) 
org.springframework.web.servlet.FrameworkServlet.processRequest(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse) (line: 967) 
org.springframework.web.servlet.FrameworkServlet.doGet(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse) (line: 858) 
javax.servlet.http.HttpServlet.service(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse) (line: 622) 
org.springframework.web.servlet.FrameworkServlet.service(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse) (line: 843) 
javax.servlet.http.HttpServlet.service(javax.servlet.ServletRequest, javax.servlet.ServletResponse) (line: 729) 
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse) (line: 292) 
org.apache.catalina.core.ApplicationFilterChain.doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse) (line: 207) 
org.apache.tomcat.websocket.server.WsFilter.doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse, javax.servlet.FilterChain) (line: 52) 
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse) (line: 240) 
org.apache.catalina.core.ApplicationFilterChain.doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse) (line: 207) 
org.springframework.web.filter.RequestContextFilter.doFilterInternal(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse, javax.servlet.FilterChain) (line: 99) 
org.springframework.web.filter.OncePerRequestFilter.doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse, javax.servlet.FilterChain) (line: 107) 
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse) (line: 240) 
org.apache.catalina.core.ApplicationFilterChain.doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse) (line: 207) 
org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse, javax.servlet.FilterChain) (line: 87) 
org.springframework.web.filter.OncePerRequestFilter.doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse, javax.servlet.FilterChain) (line: 107) 
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse) (line: 240) 
org.apache.catalina.core.ApplicationFilterChain.doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse) (line: 207) 
org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse, javax.servlet.FilterChain) (line: 77) 
org.springframework.web.filter.OncePerRequestFilter.doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse, javax.servlet.FilterChain) (line: 107) 
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse) (line: 240) 
org.apache.catalina.core.ApplicationFilterChain.doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse) (line: 207) 
org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse, javax.servlet.FilterChain) (line: 121) 
org.springframework.web.filter.OncePerRequestFilter.doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse, javax.servlet.FilterChain) (line: 107) 
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse) (line: 240) 
org.apache.catalina.core.ApplicationFilterChain.doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse) (line: 207) 
org.apache.catalina.core.StandardWrapperValve.invoke(org.apache.catalina.connector.Request, org.apache.catalina.connector.Response) (line: 212) 
org.apache.catalina.core.StandardContextValve.invoke(org.apache.catalina.connector.Request, org.apache.catalina.connector.Response) (line: 106) 
org.apache.catalina.authenticator.AuthenticatorBase.invoke(org.apache.catalina.connector.Request, org.apache.catalina.connector.Response) (line: 502) 
org.apache.catalina.core.StandardHostValve.invoke(org.apache.catalina.connector.Request, org.apache.catalina.connector.Response) (line: 141) 
org.apache.catalina.valves.ErrorReportValve.invoke(org.apache.catalina.connector.Request, org.apache.catalina.connector.Response) (line: 79) 
org.apache.catalina.core.StandardEngineValve.invoke(org.apache.catalina.connector.Request, org.apache.catalina.connector.Response) (line: 88) 
org.apache.catalina.connector.CoyoteAdapter.service(org.apache.coyote.Request, org.apache.coyote.Response) (line: 522) 
org.apache.coyote.http11.AbstractHttp11Processor.process(org.apache.tomcat.util.net.SocketWrapper) (line: 1095) 
org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(org.apache.tomcat.util.net.SocketWrapper, org.apache.tomcat.util.net.SocketStatus) (line: 672) 
org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun() (line: 1502) 
org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run() (line: 1458) 
java.util.concurrent.ThreadPoolExecutor.runWorker(java.util.concurrent.ThreadPoolExecutor$Worker) (line: 1142) 
java.util.concurrent.ThreadPoolExecutor$Worker.run() (line: 617) 
org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run() (line: 61) 
java.lang.Thread.run() (line: 745) 

I 잭슨이 모든 요청이나 시리얼 라이저를 만드는 것처럼 보입니다. 이 문제의 원인은 무엇입니까? 잭슨이나 스프링 부트 (또는 내 설정은 정말로 변경하지는 않았지만) 쪽인가요? 사용중인 Jackson 버전은 2.6.6입니다 (스프링 부트 1.3.5의 기본값).

Answer 1

Jackson은 각 요청에 대해 새로운 serializer를 만들지 않습니다. 해당 특정 라인은 간단한 동기화 블록입니다 get 조회에서 HashMap. 스레드가 경합을 일으킬 정도로 오래 지속되도록 동기화를 수행하는 것이 이상하게 보일 수 있습니다. 그래서 이것이 프로파일 링의 인공물 일지 궁금합니다.

그러나 : ObjectMapper이 첫 번째 스레드에 의해 호출 된 후에 그 메서드 자체를 많이 호출하면 안됩니다. 초기 검색이 성공한 후에는 serializer가 공유 된 맵에 추가되지만 새로 생성 된 serializer로 읽기 전용 복사본을 가져와야합니다 (SerializerProvider). 따라서 왜 계속해서 접근 할 수 있을지 의아해하고 있습니다.

아마도 jackson-databind 문제 추적기에 문제를 제기 할 수 있습니까? 2.6은 충분히 새로 워서 동작이 2.7에서도 여전히 존재합니다.