Hi Mark Thomas, Few queries from my side.
1) You have indicated it could be false positive ? But how do we confirm that ? Also, Its not just a warning, the requests are not processed any more. 2) "To be clear, no further requests can be served from the external application but internal clients can continue?" ---> Yes. For requests coming from internal clients there is no issue, Tomcat allows to process such requests. But, if it stops randomly for requests coming from external client, it will continue to stop unless tomcat is restarted. 3) "you need to upgrade as the detection got a lot better in 9.0.59 onwards." ----> does it mean, it will output more information or the issue will get solved ? 4) " Do internal and external requests go to the same connector?" ----> I think yes.... but to confirm, let me know steps I shall follow them to confirm. -----Original Message----- From: Mark Thomas <ma...@apache.org> Sent: 16 February 2023 01:13 To: users@tomcat.apache.org Subject: Re: Tomcat Issue = org.apache.tomcat.util.net.Acceptor.run Socket accept failed. java.io.IOException: Duplicate accept detected. On 15/02/2023 12:24, Patkar Omkar Anant wrote: > Hi All, > > We are facing an issue with Apache Tomcat 9. I had posted this issue in > Bugzilla forum, and from there I was re-directed here. > > The link to the bug is = > https://bz.apache.org/bugzilla/show_bug.cgi?id=66476 > > I will elaborate the details here: - > > ---------------------------------- > ERROR: - > ---------------------------------- > 10-Feb-2023 02:16:19.618 SEVERE [http-nio-80-Acceptor] > org.apache.tomcat.util.net.Acceptor.run Socket accept failed > java.io.IOException: Duplicate accept detected. This is a known OS > bug. Please consider reporting that you are affected: The only result of that error message is that the duplicate accept is ignored. It should be transparent to the client as request processing will continue on the original connection. If you see this message as a result of a false positive then the client connection will be dropped. That is obviously more problematic. > ---------------------------------- > We are using Camunda 7.16 BPMN tool which comes with inbuilt Apache Tomcat > 9.0.58. This is deployed on our Linux VM (CentOS). The VM is within our > company network, and ... via company's firewall another trusted application > on Azure cloud (outside company network)...is only allowed to make REST API > calls to Camunda (hosted on Tomcat). When Tomcat is started all works fine, > requests placed from trusted application on Azure Cloud are able to reach our > Tomcat and our application works on it, until out of the blue and randomly > above error occurs and tomcat no longer serves request coming from external > application on cloud. To be clear, no further requests can be served from the external application but internal clients can continue? > What has been tried so far ?: - > From several posts after google search it was found that Linux Kernel > version could help. Previously it was 3.x and now it is upgraded to 6.0.9-1 > and Apache Tomcat version is 9.0.58... still we face the above error. That suggests you are seeing false positives rather than the Linux bug. To avoid the false positives, you need to upgrade as the detection got a lot better in 9.0.59 onwards. > 1) Why it behaves strangely with external requests and not with internal ones > ? Do internal and external requests go to the same connector? It would be worth running Wireshark or equivalent to look at the external traffic that is being received. In particular, look at the source port for the requests once the problem starts. > 2) How can we consistently reproduce the issue ? If you want to test the original Linux bug, steps to reproduce are in the Ubuntu issue referenced in the error message. If you want to recreate the issue you are seeing (which I suspect is specific to your environment) you'll need to figure out what is happening first. > 3) What could be the possible cause and how to fix it ? Assuming you are seeing false positives with the Linux bug detection, the client using the same port for multiple requests. If the Linux bug error message is a red herring, then an Acceptor crash might explain what you are seeing. Mark --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
