For 500 instruments measurement was taking 3 minutes.

src/LoadPerformanceTest/Core/InstrumentDataPublisher.cs

@@ -1,4 +1,4 @@
-using LoadPerformanceTest.Logging;
+using LoadPerformanceTest.Logging;
 using LoadPerformanceTest.Models;
 using LoadPerformanceTest.Services.EventHub;
 using LoadPerformanceTest.Utilities;
@@ -71,7 +71,7 @@ public async Task PublishContinuouslyAsync(List<(string fileName, InstrumentData
                         break;
                     }
                 }
-                Thread.Sleep(100);
+                //Thread.Sleep(100);
             }
         });
 
@@ -147,6 +147,7 @@ private async Task PublishDataTypeContinuouslyAsync(
 
         var publishCount = 0;
         var startTime = DateTime.UtcNow;
+        var nextFireTime = DateTime.UtcNow;
         var intervalSeconds = intervalMs / 1000.0;
 
         Logger.LogInfo($"Started continuous publishing for {dataType} with {intervalSeconds} second(s) interval.");
@@ -155,32 +156,35 @@ private async Task PublishDataTypeContinuouslyAsync(
         {
             while (!cancellationToken.IsCancellationRequested)
             {
-                var updatedDataList = InstrumentDataBuilder.GenerateInstrumentDataFromInventory(jsonTemplate, _context.Tenants, dataType, _context.InstrumentManifests);
-
-                if (updatedDataList.Count > 0)
                 {
-                    int successCount = 0, failCount = 0;
+                    // Wait until next scheduled fire time
+                    var delay = nextFireTime - DateTime.UtcNow;
+                    if (delay > TimeSpan.Zero)
+                        await Task.Delay(delay, cancellationToken);
+
+                    // Skip missed cycles if publishing took longer than the interval
+                    var now = DateTime.UtcNow;
+                    while (nextFireTime <= now)
+                        nextFireTime = nextFireTime.AddMilliseconds(intervalMs);
+
+                    var updatedDataList = InstrumentDataBuilder.GenerateInstrumentDataFromInventory(jsonTemplate, _context.Tenants, dataType, _context.InstrumentManifests);
 
-                    foreach (var (updatedJson, tenantId) in updatedDataList)
+                    if (updatedDataList.Count > 0)
                     {
-                        try
-                        {
-                            await eventHubPublisher.PublishAsync(updatedJson, Path.GetFileNameWithoutExtension(fileName), tenantId, cancellationToken);
-                            successCount++;
-                        }
-                        catch (Exception ex) when (!(ex is OperationCanceledException))
-                        {
-                            failCount++;
-                            Logger.LogError($"Failed to publish {dataType} for instrument: {ex.Message}", ex);
-                        }
+                        var eventTuples = updatedDataList.Select(d => (d.json, d.tenantId));
+                        var (successCount, failCount) = await eventHubPublisher.PublishBulkAsync(
+                            eventTuples,
+                            eventType: Path.GetFileNameWithoutExtension(fileName),
+                            chunkSize: 50,
+                            maxParallelism: 9,
+                            cancellationToken: cancellationToken);
+
+                        publishCount++;
+                        var elapsed = DateTime.UtcNow - startTime;
+                        var lag = (DateTime.UtcNow - nextFireTime.AddMilliseconds(-intervalMs)).TotalSeconds;
+                        Console.WriteLine($"[{DateTime.Now:HH:mm:ss}] {dataType}: Published batch #{publishCount} - {successCount} succeeded, {failCount} failed (Running: {elapsed:hh\\:mm\\:ss}, Lag: {lag:F1}s)");
                     }
-
-                    publishCount++;
-                    var elapsed = DateTime.UtcNow - startTime;
-                    Console.WriteLine($"[{DateTime.Now:HH:mm:ss}] {dataType}: Published batch #{publishCount} - {successCount} succeeded, {failCount} failed (Running: {elapsed:hh\\:mm\\:ss})");
                 }
-
-                await Task.Delay(intervalMs, cancellationToken);
             }
         }
         catch (OperationCanceledException)

src/LoadPerformanceTest/Services/EventHub/EventHubPublisher.cs

@@ -32,6 +32,55 @@ public async Task PublishAsync(string jsonData, string eventType, string tenantI
                 throw new InvalidOperationException("Event is too large for the batch.");
 
             await _client.SendAsync(batch, cancellationToken);
+        }
+
+        /// <summary>
+        /// Publishes multiple events in parallel batches to Event Hub.
+        /// </summary>
+        public async Task<(int success, int failed)> PublishBulkAsync(
+            IEnumerable<(string JsonData, string TenantId)> events,
+            string eventType,
+            int chunkSize = 50,
+            int maxParallelism = 9,
+            CancellationToken cancellationToken = default)
+        {
+            var eventDataList = events.Select(e =>
+            {
+                var data = new EventData(Encoding.UTF8.GetBytes(e.JsonData));
+                data.Properties.Add("tenantId", e.TenantId);
+                data.Properties.Add("eventType", eventType);
+                return data;
+            }).ToList();
+
+            var chunks = eventDataList.Chunk(chunkSize);
+            int success = 0, failed = 0;
+            var lockObj = new object();
+
+            await Parallel.ForEachAsync(chunks, new ParallelOptions
+            {
+                MaxDegreeOfParallelism = maxParallelism,
+                CancellationToken = cancellationToken
+            },
+            async (chunk, ct) =>
+            {
+                try
+                {
+                    using EventDataBatch batch = await _client.CreateBatchAsync(ct);
+                    foreach (var eventData in chunk)
+                    {
+                        if (!batch.TryAdd(eventData))
+                            throw new InvalidOperationException("Event is too large for the batch.");
+                    }
+                    await _client.SendAsync(batch, ct);
+                    lock (lockObj) { success += chunk.Length; }
+                }
+                catch (Exception ex) when (ex is not OperationCanceledException)
+                {
+                    lock (lockObj) { failed += chunk.Length; }
+                }
+            });
+
+            return (success, failed);
         }
 
 

src/LoadPerformanceTest/Utilities/InstrumentDataBuilder.cs

@@ -107,7 +107,7 @@ private static void SetDataTypeSpecificFields(InstrumentData instrumentData, Ins
                                     Value = 2, // Set a dummy value or use a default/test value
                                     DecimalPrecision = def.Attributes?.DisplayDecimalPoints ?? 2,
                                     UnitId = def.UnitTypeId ?? "30d9f576-a6d2-4439-9907-7e147af64508", // Provide default if null
-                                    TimestampUtc = DateTime.UtcNow.ToClarosDateTime(),
+                                    TimestampUtc = timestamp,
                                 };
                                 instrumentData.InstrumentMeasurementDatas.Items.Add(
                                     new InstrumentMeasurementData
@@ -138,7 +138,7 @@ private static void SetDataTypeSpecificFields(InstrumentData instrumentData, Ins
                                     Value = 2, // Set a dummy value or use a default/test value
                                     DecimalPrecision = def.Attributes?.DisplayDecimalPoints ?? 2,
                                     UnitId = "30d9f576-a6d2-4439-9907-7e147af64508",
-                                    TimestampUtc = DateTime.UtcNow.ToClarosDateTime(),
+                                    TimestampUtc = timestamp,
                                 };
                                 instrumentData.InstrumentMeasurementDatas.Items.Add(
                                     new InstrumentMeasurementData
@@ -206,7 +206,7 @@ public static ClarosJsonTicksDateTime ToClarosDateTime(this DateTime dateTime)
     {
         return new ClarosJsonTicksDateTime
         {
-            JsonDateTime = dateTime.ToUtc().ToString("O")
+            Ticks = (ulong)dateTime.ToUtc().Ticks
         };
     }