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Default configuration tops out at 1024 connections [message #1855645]

Tue, 25 October 2022 14:09

Gambit Support

Messages: 46
Registered: March 2019

Member

We followed the instructions at

https://amlen.org/index.php/2022/02/21/the-long-winded-guide-to-setting-up-amlen-introduction/

and can get 1000+ connections to the Amlen server out of the box.
See screenshot.

But there seems to be a limit of 1024. We have encountered this many times
before with other brokers, but cannot figure out where this is in Amlen. Usually it is
the "limits" for open files of the process, which does not seem to be the case for
imaserver.

Any help would be appreciated.

Attachment: mimic-amlen-1024.png
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Re: Default configuration tops out at 1024 connections [message #1855646 is a reply to message #1855645]

Tue, 25 October 2022 14:19

Ian Boden

Messages: 2
Registered: August 2021

Junior Member

Hi,

I'm not aware of anything you would need to do to go above 1024 connections out of the box. Do you have logs showing what happens when the 1025th connection is attempted? Is it the connection that fails or is it failing when subscribbing? The imatrace.log file might also give a clue as to what is going on.

Ian

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Re: Default configuration tops out at 1024 connections [message #1855648 is a reply to message #1855645]

Tue, 25 October 2022 15:08

Eric Klingelberger

Messages: 5
Registered: July 2009

Junior Member

If you are running imaserver outside of docker then ensure that /etc/security/limits.conf is configured such that the nofile limit is greater than the expected concurrent connection count.

If you are running imaserver inside of docker then you can pass the ulimit to the docker run command. For example, docker run --ulimit nofile=262144:262144

The imaserver log file contains the computed max allowed TCP connections. Look for a log message like this.

"Set maximum TCP connections: %d\n"

Here is where the max TCP connections is logged in the code: https://github.com/eclipse/amlen/blob/main/server_transport/src/tcp.c#L2926

imaserver will also establish an upper bound on concurrent TCP connections based on available memory. 4K concurrent connections per GB of memory allocated to the imaserver process, is the rule of thumb.

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