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Fix Lite perfmon chart bugs and Dashboard ScottPlot crash handling #546

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Merged
erikdarlingdata merged 1 commit into from
Mar 13, 2026
+75 −37
Merged

Fix Lite perfmon chart bugs and Dashboard ScottPlot crash handling #546

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21 changes: 20 additions & 1 deletion Dashboard/MainWindow.xaml.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -502,7 +502,26 @@ private async Task OpenServerTabAsync(ServerConnection server)
var utcOffset = connStatus.UtcOffsetMinutes ?? (int)TimeZoneInfo.Local.GetUtcOffset(DateTime.UtcNow).TotalMinutes;
Helpers.ServerTimeHelper.UtcOffsetMinutes = utcOffset;

var serverTab = new ServerTab(server, utcOffset);
ServerTab serverTab;
try
{
serverTab = new ServerTab(server, utcOffset);
}
catch (Exception ex)
{
var inner = ex.InnerException?.Message ?? ex.Message;
System.Windows.MessageBox.Show(
$"Failed to open server tab for '{server.DisplayName}'.\n\n" +
$"This is usually caused by a missing Visual C++ Redistributable (x64) " +
$"or an OS compatibility issue with the SkiaSharp rendering library.\n\n" +
$"Download the latest VC++ Redistributable from:\n" +
$"https://aka.ms/vs/17/release/vc_redist.x64.exe\n\n" +
$"Error: {inner}",
"Chart Initialization Error",
System.Windows.MessageBoxButton.OK,
System.Windows.MessageBoxImage.Error);
return;
}
serverTab.AlertAcknowledged += (_, _) =>
{
_emailAlertService.HideAllAlerts(8760, server.DisplayName);
Expand Down
78 changes: 47 additions & 31 deletions Lite/Services/DeltaCalculator.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -24,9 +24,9 @@ namespace PerformanceMonitorLite.Services;
public class DeltaCalculator
{
/// <summary>
/// Cache structure: serverId -> collectorName -> key -> previousValue
/// Cache structure: serverId -> collectorName -> key -> (previousValue, timestamp)
/// </summary>
private readonly ConcurrentDictionary<int, ConcurrentDictionary<string, ConcurrentDictionary<string, long>>> _cache = new();
private readonly ConcurrentDictionary<int, ConcurrentDictionary<string, ConcurrentDictionary<string, (long Value, DateTime? Timestamp)>>> _cache = new();

private readonly ILogger? _logger;

Expand Down Expand Up @@ -63,12 +63,15 @@ public async Task SeedFromDatabaseAsync(DuckDbInitializer duckDb)
/// Calculates the delta between the current value and the previous cached value.
/// First-ever sighting (no baseline): returns currentValue so single-execution queries appear.
/// Counter reset (value decreased): returns 0 to avoid inflated deltas from plan cache churn.
/// Gap detection: if collectionTime and maxGapSeconds are provided and the gap since the
/// last cached value exceeds maxGapSeconds, returns 0 to avoid inflated deltas after restarts.
/// Thread-safe via atomic AddOrUpdate.
/// </summary>
public long CalculateDelta(int serverId, string collectorName, string key, long currentValue, bool baselineOnly = false)
public long CalculateDelta(int serverId, string collectorName, string key, long currentValue,
bool baselineOnly = false, DateTime? collectionTime = null, int maxGapSeconds = 0)
{
var serverCache = _cache.GetOrAdd(serverId, _ => new ConcurrentDictionary<string, ConcurrentDictionary<string, long>>());
var collectorCache = serverCache.GetOrAdd(collectorName, _ => new ConcurrentDictionary<string, long>());
var serverCache = _cache.GetOrAdd(serverId, _ => new ConcurrentDictionary<string, ConcurrentDictionary<string, (long Value, DateTime? Timestamp)>>());
var collectorCache = serverCache.GetOrAdd(collectorName, _ => new ConcurrentDictionary<string, (long Value, DateTime? Timestamp)>());

long delta = 0;

Expand All @@ -80,15 +83,24 @@ public long CalculateDelta(int serverId, string collectorName, string key, long
_ =>
{
delta = baselineOnly ? 0 : currentValue;
return currentValue;
return (currentValue, collectionTime);
},
/* Update: compute delta atomically */
(_, previousValue) =>
(_, previous) =>
{
delta = currentValue < previousValue
/* Gap detection: if too much time has passed since the last cached value,
treat this as a new baseline to avoid inflated deltas after app restarts */
if (maxGapSeconds > 0 && collectionTime.HasValue && previous.Timestamp.HasValue
&& (collectionTime.Value - previous.Timestamp.Value).TotalSeconds > maxGapSeconds)
{
delta = 0;
return (currentValue, collectionTime);
}

delta = currentValue < previous.Value
? 0 /* counter reset (plan cache eviction/re-entry) — not real new work */
: currentValue - previousValue;
return currentValue;
: currentValue - previous.Value;
return (currentValue, collectionTime);
});

return delta;
Expand All @@ -97,18 +109,18 @@ public long CalculateDelta(int serverId, string collectorName, string key, long
/// <summary>
/// Seeds a single value into the cache without computing a delta.
/// </summary>
private void Seed(int serverId, string collectorName, string key, long value)
private void Seed(int serverId, string collectorName, string key, long value, DateTime? timestamp = null)
{
var serverCache = _cache.GetOrAdd(serverId, _ => new ConcurrentDictionary<string, ConcurrentDictionary<string, long>>());
var collectorCache = serverCache.GetOrAdd(collectorName, _ => new ConcurrentDictionary<string, long>());
collectorCache[key] = value;
var serverCache = _cache.GetOrAdd(serverId, _ => new ConcurrentDictionary<string, ConcurrentDictionary<string, (long Value, DateTime? Timestamp)>>());
var collectorCache = serverCache.GetOrAdd(collectorName, _ => new ConcurrentDictionary<string, (long Value, DateTime? Timestamp)>());
collectorCache[key] = (value, timestamp);
}

private async Task SeedWaitStatsAsync(DuckDBConnection connection)
{
using var cmd = connection.CreateCommand();
cmd.CommandText = @"
SELECT server_id, wait_type, waiting_tasks_count, wait_time_ms, signal_wait_time_ms
SELECT server_id, wait_type, waiting_tasks_count, wait_time_ms, signal_wait_time_ms, collection_time
FROM wait_stats
WHERE (server_id, collection_time) IN (
SELECT server_id, MAX(collection_time) FROM wait_stats GROUP BY server_id
Expand All @@ -119,9 +131,10 @@ FROM wait_stats
{
var serverId = reader.GetInt32(0);
var waitType = reader.GetString(1);
Seed(serverId, "wait_stats_tasks", waitType, reader.GetInt64(2));
Seed(serverId, "wait_stats_time", waitType, reader.GetInt64(3));
Seed(serverId, "wait_stats_signal", waitType, reader.GetInt64(4));
var ts = reader.IsDBNull(5) ? (DateTime?)null : reader.GetDateTime(5);
Seed(serverId, "wait_stats_tasks", waitType, reader.GetInt64(2), ts);
Seed(serverId, "wait_stats_time", waitType, reader.GetInt64(3), ts);
Seed(serverId, "wait_stats_signal", waitType, reader.GetInt64(4), ts);
count++;
}
if (count > 0) _logger?.LogDebug("Seeded {Count} wait_stats baseline rows", count);
Expand All @@ -134,7 +147,8 @@ private async Task SeedFileIoStatsAsync(DuckDBConnection connection)
SELECT server_id, database_name, file_name,
num_of_reads, num_of_writes, read_bytes, write_bytes,
io_stall_read_ms, io_stall_write_ms,
io_stall_queued_read_ms, io_stall_queued_write_ms
io_stall_queued_read_ms, io_stall_queued_write_ms,
collection_time
FROM file_io_stats
WHERE (server_id, collection_time) IN (
SELECT server_id, MAX(collection_time) FROM file_io_stats GROUP BY server_id
Expand All @@ -147,14 +161,15 @@ FROM file_io_stats
var dbName = reader.IsDBNull(1) ? "" : reader.GetString(1);
var fileName = reader.IsDBNull(2) ? "" : reader.GetString(2);
var deltaKey = $"{dbName}|{fileName}";
Seed(serverId, "file_io_reads", deltaKey, reader.IsDBNull(3) ? 0 : reader.GetInt64(3));
Seed(serverId, "file_io_writes", deltaKey, reader.IsDBNull(4) ? 0 : reader.GetInt64(4));
Seed(serverId, "file_io_read_bytes", deltaKey, reader.IsDBNull(5) ? 0 : reader.GetInt64(5));
Seed(serverId, "file_io_write_bytes", deltaKey, reader.IsDBNull(6) ? 0 : reader.GetInt64(6));
Seed(serverId, "file_io_stall_read", deltaKey, reader.IsDBNull(7) ? 0 : reader.GetInt64(7));
Seed(serverId, "file_io_stall_write", deltaKey, reader.IsDBNull(8) ? 0 : reader.GetInt64(8));
Seed(serverId, "file_io_stall_queued_read", deltaKey, reader.IsDBNull(9) ? 0 : reader.GetInt64(9));
Seed(serverId, "file_io_stall_queued_write", deltaKey, reader.IsDBNull(10) ? 0 : reader.GetInt64(10));
var ts = reader.IsDBNull(11) ? (DateTime?)null : reader.GetDateTime(11);
Seed(serverId, "file_io_reads", deltaKey, reader.IsDBNull(3) ? 0 : reader.GetInt64(3), ts);
Seed(serverId, "file_io_writes", deltaKey, reader.IsDBNull(4) ? 0 : reader.GetInt64(4), ts);
Seed(serverId, "file_io_read_bytes", deltaKey, reader.IsDBNull(5) ? 0 : reader.GetInt64(5), ts);
Seed(serverId, "file_io_write_bytes", deltaKey, reader.IsDBNull(6) ? 0 : reader.GetInt64(6), ts);
Seed(serverId, "file_io_stall_read", deltaKey, reader.IsDBNull(7) ? 0 : reader.GetInt64(7), ts);
Seed(serverId, "file_io_stall_write", deltaKey, reader.IsDBNull(8) ? 0 : reader.GetInt64(8), ts);
Seed(serverId, "file_io_stall_queued_read", deltaKey, reader.IsDBNull(9) ? 0 : reader.GetInt64(9), ts);
Seed(serverId, "file_io_stall_queued_write", deltaKey, reader.IsDBNull(10) ? 0 : reader.GetInt64(10), ts);
count++;
}
if (count > 0) _logger?.LogDebug("Seeded {Count} file_io_stats baseline rows", count);
Expand All @@ -164,7 +179,7 @@ private async Task SeedPerfmonStatsAsync(DuckDBConnection connection)
{
using var cmd = connection.CreateCommand();
cmd.CommandText = @"
SELECT server_id, object_name, counter_name, instance_name, cntr_value
SELECT server_id, object_name, counter_name, instance_name, cntr_value, collection_time
FROM perfmon_stats
WHERE (server_id, collection_time) IN (
SELECT server_id, MAX(collection_time) FROM perfmon_stats GROUP BY server_id
Expand All @@ -177,7 +192,8 @@ FROM perfmon_stats
var objectName = reader.IsDBNull(1) ? "" : reader.GetString(1);
var counter = reader.IsDBNull(2) ? "" : reader.GetString(2);
var instance = reader.IsDBNull(3) ? "" : reader.GetString(3);
Seed(serverId, "perfmon", $"{objectName}|{counter}|{instance}", reader.GetInt64(4));
var ts = reader.IsDBNull(5) ? (DateTime?)null : reader.GetDateTime(5);
Seed(serverId, "perfmon", $"{objectName}|{counter}|{instance}", reader.GetInt64(4), ts);
count++;
}
if (count > 0) _logger?.LogDebug("Seeded {Count} perfmon_stats baseline rows", count);
Expand All @@ -202,8 +218,8 @@ FROM memory_grant_stats
var poolId = reader.IsDBNull(1) ? 0 : reader.GetInt32(1);
var semaphoreId = reader.IsDBNull(2) ? (short)0 : reader.GetInt16(2);
var deltaKey = $"{poolId}_{semaphoreId}";
Seed(serverId, "memory_grants_timeouts", deltaKey, reader.IsDBNull(3) ? 0 : reader.GetInt64(3));
Seed(serverId, "memory_grants_forced", deltaKey, reader.IsDBNull(4) ? 0 : reader.GetInt64(4));
Seed(serverId, "memory_grants_timeouts", deltaKey, reader.IsDBNull(3) ? 0 : reader.GetInt64(3), null);
Seed(serverId, "memory_grants_forced", deltaKey, reader.IsDBNull(4) ? 0 : reader.GetInt64(4), null);
count++;
}
if (count > 0) _logger?.LogDebug("Seeded {Count} memory_grant_stats baseline rows", count);
Expand Down
5 changes: 3 additions & 2 deletions Lite/Services/LocalDataService.Perfmon.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -95,13 +95,14 @@ public async Task<List<PerfmonTrendPoint>> GetPerfmonTrendAsync(int serverId, st
command.CommandText = @"
SELECT
collection_time,
cntr_value,
delta_cntr_value
SUM(cntr_value) AS cntr_value,
SUM(delta_cntr_value) AS delta_cntr_value
FROM v_perfmon_stats
WHERE server_id = $1
AND counter_name = $2
AND collection_time >= $3
AND collection_time <= $4
GROUP BY collection_time
ORDER BY collection_time";

command.Parameters.Add(new DuckDBParameter { Value = serverId });
Expand Down
8 changes: 5 additions & 3 deletions Lite/Services/RemoteCollectorService.Perfmon.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -178,9 +178,11 @@ WHERE pc.counter_name IN (
var instanceName = reader.IsDBNull(2) ? "" : reader.GetString(2);
var cntrValue = reader.GetInt64(3);

/* Delta for per-second counters */
/* Delta for per-second counters — gap detection at 5min (5x the 1-min collection interval)
prevents inflated deltas after app restarts */
var deltaKey = $"{objectName}|{counterName}|{instanceName}";
var deltaCntrValue = _deltaCalculator.CalculateDelta(serverId, "perfmon", deltaKey, cntrValue, baselineOnly: true);
var deltaCntrValue = _deltaCalculator.CalculateDelta(serverId, "perfmon", deltaKey, cntrValue,
baselineOnly: true, collectionTime: collectionTime, maxGapSeconds: 300);

var row = appender.CreateRow();
row.AppendValue(GenerateCollectionId())
Expand All @@ -192,7 +194,7 @@ WHERE pc.counter_name IN (
.AppendValue(instanceName)
.AppendValue(cntrValue)
.AppendValue(deltaCntrValue)
.AppendValue(600) /* 10-minute interval */
.AppendValue(60) /* 1-minute collection interval */
.EndRow();

rowsCollected++;
Expand Down
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