I am impacted by this bug as well, as reported in my Tomcat 9-based
application logs:
[2022-04-18 21:45:44.764] ERROR [http-nio-9083-Acceptor ]
org.apache.tomcat.util.net.Acceptor Socket accept failed
java.io.IOException: Duplicate accept detected. This is a known OS bug.
Please consider reporting that you are affected:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1924298
This app runs on AWS ECS Fargate v1.4 in a Ubuntu 18.04 amd64 based
image using the BellSoft Liberica JRE 11. I get this log messages a
couple times a day on average.
The application continues running, seemingly without any problems. The
ERROR log trigger alerts which we will adapt to ignore, but I wanted to
add my experience with this issue here.
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https://bugs.launchpad.net/bugs/1924298
Title:
accept returns duplicate endpoints under load
Status in Linux:
New
Status in linux package in Ubuntu:
Confirmed
Bug description:
When accepting client connections under load, duplicate endpoints may
be returned. These endpoints will have different (usually sequential)
file descriptors but will refer to the same connection (same server
IP, same server port, same client IP, same client port). Both copies
of the endpoint appear to be functional.
Reproduction requires:
- compilation of the attached server.c program
- wrk (https://github.com/wg/wrk) to generate load
The steps to reproduce are:
- run 'server' application in one console window
- run 'for i in {1..50}; do /opt/wrk/wrk -t 2 -c 1000 -d 5s --latency
--timeout 1s http://localhost:5555/post; done' in a second console window
- run the same command in a third window to generate concurrent load
You may need to run additional instance of the wrk command in multiple
windows to trigger the issue.
When the problem occurs the server executable will exit and print some
debugging info. e.g.:
accerror = 1950892, counter = 10683, port = 59892, clientfd = 233, lastClient
= 232
This indicates that the sockets with file descriptors 233 and 232 are
duplicates.
The issue has been reproduced on fully patched versions of Ubuntu
20.04 and 18.04. Other versions have not been tested.
This issue was originally observed in Java and was reported against the
Spring Framework:
https://github.com/spring-projects/spring-framework/issues/26434
Investigation from the Spring team and the Apache Tomcat team identified that
it appeared to be a JDK issue:
https://bugs.openjdk.java.net/browse/JDK-8263243
Further research from the JDK team determined that the issue was at
the OS level. Hence this report.
ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: linux-image-5.4.0-71-generic 5.4.0-71.79
ProcVersionSignature: Ubuntu 5.4.0-71.79-generic 5.4.101
Uname: Linux 5.4.0-71-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.11-0ubuntu27.16
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Thu Apr 15 12:52:53 2021
HibernationDevice: RESUME=UUID=f5a46e09-d99b-4475-8ab6-2cd70da8418d
InstallationDate: Installed on 2017-02-02 (1532 days ago)
InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64
(20160719)
IwConfig:
lo no wireless extensions.
docker0 no wireless extensions.
eno1 no wireless extensions.
MachineType: Gigabyte Technology Co., Ltd. Default string
ProcFB: 0 VESA VGA
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-5.4.0-71-generic
root=/dev/mapper/ubuntu--vg-root ro text
RelatedPackageVersions:
linux-restricted-modules-5.4.0-71-generic N/A
linux-backports-modules-5.4.0-71-generic N/A
linux-firmware 1.187.10
RfKill:
SourcePackage: linux
UpgradeStatus: Upgraded to focal on 2020-09-07 (219 days ago)
dmi.bios.date: 06/13/2016
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: F22
dmi.board.asset.tag: Default string
dmi.board.name: X99-SLI-CF
dmi.board.vendor: Gigabyte Technology Co., Ltd.
dmi.board.version: x.x
dmi.chassis.asset.tag: Default string
dmi.chassis.type: 3
dmi.chassis.vendor: Default string
dmi.chassis.version: Default string
dmi.modalias:
dmi:bvnAmericanMegatrendsInc.:bvrF22:bd06/13/2016:svnGigabyteTechnologyCo.,Ltd.:pnDefaultstring:pvrDefaultstring:rvnGigabyteTechnologyCo.,Ltd.:rnX99-SLI-CF:rvrx.x:cvnDefaultstring:ct3:cvrDefaultstring:
dmi.product.family: Default string
dmi.product.name: Default string
dmi.product.sku: Default string
dmi.product.version: Default string
dmi.sys.vendor: Gigabyte Technology Co., Ltd.
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