First heartbeat sent after 15 minutes instead of configured interval

[xavierdecoster]

It appears that the very first heartbeat is sent after 15 minutes, which is the default built-in heartbeat interval, even when a different interval is configured. Every other subsequent heartbeat will respect the configured interval.

SDK version used: 2.10.0

Attached some code that reproduces the issue.

Expected behavior: heartbeats start after the very first minute (as configured)
Actual behavior: heartbeats only start after 15 minutes (default interval)

ConsoleApp1.zip

[cijothomas]

Its a bug/limitation as setting interval does not alter the current timer, which is triggered upon initialize.
https://github.com/microsoft/ApplicationInsights-dotnet/blob/develop/BASE/src/Microsoft.ApplicationInsights/Managed/Shared/Extensibility/Implementation/Tracing/HeartbeatProvider.cs#L91

Use the following workaround:
Basically, don't use .Active, instead create DiagnosticTelemetryModule by yourself, so that you can interval before initializing it.

static void Main(string[] args)
{

        var tc = new TelemetryConfiguration("ikey");
        var diagModule = new DiagnosticsTelemetryModule();
        diagModule.HeartbeatInterval = TimeSpan.FromSeconds(30);
        diagModule.Initialize(tc);
        
        while(true)
        {

        }
    }

(Modify example as per your requirement, but this should give you the idea)

[xavierdecoster]

@cijothomas does the call to new TelemetryConfiguration("ikey") still consider the applicationinsights.config file? Or should we rely on TelemetryConfiguration.CreateDefault() instead, and then set TelemetryConfiguration.InstrumentationKey on that instance?

[cijothomas]

new TelemetryConfiguration("ikey") wont consider ai.config.