Why Does OtlpExporterOptions.ExportProcessorType Not Work for Setting Simple Export Mode?

[madhub]

Description

When setting ExportProcessorType.Simple on OtlpExporterOptions to select synchronous export, it doesn't work as expected. By default, it continues to select BatchLogRecordExportProcessor as the option. The setting only works when using ExportProcessorTypein LogRecordExportProcessorOptions.

This raises a question: What is the purpose of OtlpExporterOptions.ExportProcessorType if I need to set non-batch mode on LogRecordExportProcessorOptions? This behavior is confusing and inconsistent.

This code doesn't seem to work - still uses BatchLogRecordExportProcessor

using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using OpenTelemetry.Resources;
using OpenTelemetry.Exporter;
using Microsoft.Extensions.Configuration;
using OpenTelemetry.Logs;
using Microsoft.Extensions.Logging;
using OpenTelemetry;

HostApplicationBuilder hostApplicationBuilder = Host.CreateApplicationBuilder(args);

hostApplicationBuilder.Services.AddOpenTelemetry()
    .ConfigureResource(resourceBuilder => {
        resourceBuilder.AddService(
            serviceName: hostApplicationBuilder.Configuration.GetValue("ServiceName", defaultValue: "otel-test")!,
            serviceVersion: typeof(Program).Assembly.GetName().Version?.ToString() ?? "unknown",
            serviceInstanceId: Environment.MachineName);
    })
    .WithLogging(builder =>
    {
        builder.AddOtlpExporter(otlpOptions =>
        {
            // This setting doesn't seem to work - still uses BatchLogRecordExportProcessor
            otlpOptions.ExportProcessorType = ExportProcessorType.Simple;
        });
    });

using IHost host = hostApplicationBuilder.Build();
var logger = host.Services.GetRequiredService<ILogger<Program>>();
logger.LogInformation("OpenTelemetry logging is configured.");

await host.RunAsync();

Expected vs Actual Behavior

Expected: Setting otlpOptions.ExportProcessorType = ExportProcessorType.Simpleshould configure the exporter to use simple (synchronous) export processing
Actual: The setting appears to be ignored, and BatchLogRecordExportProcessor is still used by default

Workaround

The workaround requires using the overload that provides access to LogRecordExportProcessorOptions:

.WithLogging(builder =>
{
    builder.AddOtlpExporter((otlpOptions, logRecordExportProcessorOptions) =>
    {
        logRecordExportProcessorOptions.ExportProcessorType = ExportProcessorType.Simple;
        // Use IConfiguration directly for Otlp exporter endpoint option.
        //otlpOptions.Endpoint = new Uri(hostApplicationBuilder.Configuration.GetValue("Otlp:Endpoint", defaultValue: "http://localhost:4317"));
        // use default endpoint
    });
});

Questions

1. Is OtlpExporterOptions.ExportProcessorType intended to be functional, or is it deprecated?
2. Should the export processor type always be configured via the LogRecordExportProcessorOptions parameter rather than the OtlpExporterOptions?
3. Is this inconsistent behavior a bug or by design?
4. Why do we have two different places to set the same ExportProcessorType property, and which one takes precedence?

The current API design is confusing because it suggests that OtlpExporterOptions.ExportProcessorType should control the processor type, but in practice, only the LogRecordExportProcessorOptions.ExportProcessorType setting appears to work.