[fbarresi]

Since AMQPNetLite v2.4.8 the IdleTimeOut supports negative values.
The new default value is -1.
If the timeout of -1 get casted to uint it becames uint.MaxValue.
This lead to wrong working heartbeat and high CPU usage.

Below a detailled explaination about the issue and how to reproduce it.

How to reproduce the issue

This issue occurs every time you attempt to use a newer version of the AmqpNetLite.Core. The Nuget package for ApacheNMS.AMQP requires AMQPNetLite.Core >= 2.4.3 .
Up to version 2.4.7, there is no meaningful difference in the behavior of the library.
Starting on the version 2.4.8 and newer, I detected an high CPU consumption during idle.

This can be easily reproduced in this way:

1. Create an empty project and reference the AMQPNetLite.Core explicitly.

example.csproj

<Project Sdk="Microsoft.NET.Sdk">

    <PropertyGroup>
        <OutputType>Exe</OutputType>
        <TargetFramework>net8.0</TargetFramework>
        <ImplicitUsings>enable</ImplicitUsings>
        <Nullable>enable</Nullable>
    </PropertyGroup>

    <ItemGroup>
        <PackageReference Include="AMQPNetLite.Core" Version="2.4.7" />
        <PackageReference Include="Apache.NMS" Version="2.2.0" />
        <PackageReference Include="Apache.NMS.AMQP" Version="2.4.0" />
    </ItemGroup>

</Project>

Program.cs

using Apache.NMS;

var connectionString = new Uri(Environment.GetEnvironmentVariable("ConnectionString")!);

var username = Environment.GetEnvironmentVariable("Username");
var password = Environment.GetEnvironmentVariable("Password");

var connection = new NMSConnectionFactory(connectionString, Array.Empty<object>())
    .CreateConnection(username, password);
var session = connection.CreateSession();

connection.Start();

Console.WriteLine("Press enter to exit...");
Console.ReadLine();

2. Check the Performance differences between AMQPNetLite.Core 2.4.7 and 2.4.8.

• 2.4.7
  Apart of some initial activity, you see 0% CPU usage

• 2.4.8
  The CPU goes high up to 20% while the program is actually be in idle the whole time (no producers neither consumers)

In a containerized application with low memory and CPU quota grant, it goes even higher.

How/why this occurs

The apache.nsm.amqp library performs a casting from the default value (if not overriden):

this lead to an unintended value in case of -1, the new default value fo this setting:

Proposed solution

Since the underlaying library AmqpNetLite.Core changed the default value and its behavior in this matter, I think the apache.nsm.amqp should perfom a casting only if the IdleTimeOut is not negative and pass 0 elsewhere. This will allow to keep a low dependency requirement, remain backward capable and also fit newer version of AMQPNetLite.Core.

[davidvoit]

Maybe this pull request can be combined with an upgrade to amqpnetlite 2.5.x? @Havret is this something which would make sense or is this something which should be a different pull request?

[Havret]

Maybe this pull request can be combined with an upgrade to amqpnetlite 2.5.x? @Havret is this something which would make sense or is this something which should be a different pull request?

I think it would make better sense to bump amqpnetlite in a separate PR.

[Copilot]

Pull request overview

Adjusts AMQP Open handshake negotiation to avoid overflowing IdleTimeOut when using AMQPNetLite.Core >= 2.4.8 (where the default IdleTimeout can be -1), preventing incorrect heartbeat scheduling that can lead to high CPU usage during idle periods.

Changes:

• Guarded the Open.IdleTimeOut assignment to only cast positive values to uint, otherwise send 0.

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[fbarresi]

Dear @Havret , thank you for your review. I applied the changes and updated the PR.

[Havret]

Will need some follow up work. But I will take care of it with a separate PR.