Spring Boot v1.4 - Processing of multipart/form-data request failed. null] with root cause java.net.SocketTimeoutException: null - spring-boot

Question

I have a 1000s of IOT devices continuously sending data in form of small files (1 Kb approx) to my Spring-Boot Application server.
I keep getting this error at specific intervals. Could someone point out what is wrong?
I have Controllers to upload files as well as a TCP socket.
ERROR 37762 --- [io-8080-exec-29] o.a.c.c.C.[.[.[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.web.multipart.MultipartException: Could not parse multipart servlet request; nested exception is java.io.IOException: org.apache.tomcat.util.http.fileupload.FileUploadBase$IOFileUploadException: Processing of multipart/form-data request failed. null] with root cause
java.net.SocketTimeoutException: null
at org.apache.tomcat.util.net.NioBlockingSelector.read(NioBlockingSelector.java:201)
at org.apache.tomcat.util.net.NioSelectorPool.read(NioSelectorPool.java:235)
at org.apache.tomcat.util.net.NioSelectorPool.read(NioSelectorPool.java:216)
at org.apache.tomcat.util.net.NioEndpoint$NioSocketWrapper.fillReadBuffer(NioEndpoint.java:1212)
at org.apache.tomcat.util.net.NioEndpoint$NioSocketWrapper.read(NioEndpoint.java:1163)
at org.apache.coyote.http11.Http11InputBuffer.fill(Http11InputBuffer.java:742)
at org.apache.coyote.http11.Http11InputBuffer.access$400(Http11InputBuffer.java:38)
at org.apache.coyote.http11.Http11InputBuffer$SocketInputBuffer.doRead(Http11InputBuffer.java:1073)
at org.apache.coyote.http11.filters.IdentityInputFilter.doRead(IdentityInputFilter.java:100)
at org.apache.coyote.http11.Http11InputBuffer.doRead(Http11InputBuffer.java:303)
at org.apache.coyote.Request.doRead(Request.java:511)
at org.apache.catalina.connector.InputBuffer.realReadBytes(InputBuffer.java:318)
at org.apache.tomcat.util.buf.ByteChunk.checkEof(ByteChunk.java:397)
at org.apache.tomcat.util.buf.ByteChunk.substract(ByteChunk.java:379)
at org.apache.catalina.connector.InputBuffer.read(InputBuffer.java:338)
at org.apache.catalina.connector.CoyoteInputStream.read(CoyoteInputStream.java:189)
at java.io.FilterInputStream.read(FilterInputStream.java:133)
at org.apache.tomcat.util.http.fileupload.util.LimitedInputStream.read(LimitedInputStream.java:132)
at org.apache.tomcat.util.http.fileupload.MultipartStream$ItemInputStream.makeAvailable(MultipartStream.java:946)
at org.apache.tomcat.util.http.fileupload.MultipartStream$ItemInputStream.read(MultipartStream.java:850)
at java.io.FilterInputStream.read(FilterInputStream.java:133)
at org.apache.tomcat.util.http.fileupload.util.LimitedInputStream.read(LimitedInputStream.java:132)
at java.io.FilterInputStream.read(FilterInputStream.java:107)
at org.apache.tomcat.util.http.fileupload.util.Streams.copy(Streams.java:98)
at org.apache.tomcat.util.http.fileupload.util.Streams.copy(Streams.java:68)
at org.apache.tomcat.util.http.fileupload.FileUploadBase.parseRequest(FileUploadBase.java:293)
at org.apache.catalina.connector.Request.parseParts(Request.java:2792)
at org.apache.catalina.connector.Request.parseParameters(Request.java:3167)
at org.apache.catalina.connector.Request.getParameter(Request.java:1109)
at org.apache.catalina.connector.RequestFacade.getParameter(RequestFacade.java:381)
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:70)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:108)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:522)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:349)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:1110)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:785)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1425)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:748)

Answer 1

A firewall may drop a TCP connection that has been inactive for a longer period. A solution is to send TCP keepalives.
Check also that both the maximum amount of connection through the firewall, and that the maximum number of OS file descriptors is not exceeded.