Monitoring PI Buffering Subsystem Queue: Options & Best Practices

When working with OSIsoft PI buffering (pibufss), it's natural to wonder how you can programmatically check if the buffering subsystem queue is empty—especially for robust troubleshooting and automation scenarios. Many engineers first turn to the AF SDK, but current public APIs have limitations in this area.

AF SDK Limitations

While AF SDK does include the PIBufferStatus.Health property (representing the overall health of the buffering system), it does not expose granular details about the number of currently buffered (queued) events. The health status is great for identifying issues at a high level, but it doesn't answer directly whether the buffer is empty or how many events might be pending transmission.

The Recommended Approach: PerfMon Counters

The best alternative is to leverage Windows Performance Monitor (PerfMon) counters, specifically those provided by pibufss. PerfMon exposes a counter called Queued Events, which directly reports the number of PI events currently buffered and awaiting transfer.

How to Access the Counter

• Manually via PerfMon: Launch Performance Monitor on the relevant PI interface or client node, add the pibufss object, and watch the Queued Events counter in real time.
• Programmatically (C#, PowerShell, etc.): Use .NET’s System.Diagnostics.PerformanceCounter class or similar libraries to read the value of the "Queued Events" counter. This can be integrated into custom monitoring tools or dashboards.

// Example: Reading the Queued Events Counter in C#
var counter = new System.Diagnostics.PerformanceCounter(
    "pibufss",
    "Queued Events",
    instanceName: "_Total"
);
float queued = counter.NextValue();
Console.WriteLine($"Current queued events: {queued}");

This approach provides a real-time, programmatically accessible metric unavailable through the AFSDK.

Why This Matters

Knowing whether your PI buffer queue is empty is crucial for:

• Troubleshooting data flow issues
• Automated deployment or switchover scripts (ensuring all events are sent)
• Capacity and health monitoring

Got a Special Use Case?

If you need more tailored solutions (e.g., for specific alerting/automation scenarios), sharing the use case with the community or OSIsoft technical support is recommended. There may be advanced or alternative options based on your site's architecture or third-party integrations.

Summary

Directly checking the emptiness of the PI buffering subsystem queue using AF SDK isn’t possible. Instead, use Windows PerfMon’s Queued Events for reliable insight. This is a best-practice approach embraced by seasoned PI System engineers.

References:

• PI Buffer Subsystem Documentation (OSIsoft)
• System.Diagnostics.PerformanceCounter Class (Microsoft Docs)