Fix parsing configuration for TraceIdRatioBasedSampler on non standard locales + fix localization related test

src/OpenTelemetry/CHANGELOG.md

@@ -25,6 +25,11 @@ Notes](../../RELEASENOTES.md).
   }
   ```
 
+* Fixed parsing of `OTEL_TRACES_SAMPLER_ARG` decimal values to always use `.`
+  as the delimiter when using the `traceidratio` sampler, preventing
+  locale-specific parsing issues.
+  ([#6444](https://github.com/open-telemetry/opentelemetry-dotnet/pull/6444))
+
 ## 1.12.0
 
 Released 2025-Apr-29

src/OpenTelemetry/Trace/TracerProviderSdk.cs

@@ -2,6 +2,7 @@
 // SPDX-License-Identifier: Apache-2.0
 
 using System.Diagnostics;
+using System.Globalization;
 using System.Runtime.CompilerServices;
 using System.Text;
 using System.Text.RegularExpressions;
@@ -458,7 +459,7 @@ private static Sampler GetSampler(IConfiguration configuration, Sampler? stateSa
     private static double ReadTraceIdRatio(IConfiguration configuration)
     {
         if (configuration.TryGetStringValue(TracesSamplerArgConfigKey, out var configValue) &&
-                double.TryParse(configValue, out var traceIdRatio))
+                double.TryParse(configValue, NumberStyles.Float | NumberStyles.AllowThousands, CultureInfo.InvariantCulture, out var traceIdRatio))
         {
             return traceIdRatio;
         }

test/OpenTelemetry.Tests/Logs/LogRecordTests.cs

@@ -246,11 +246,12 @@ public void CheckStateForStructuredLogWithGeneralType(bool includeFormattedMessa
     {
         using var loggerFactory = InitializeLoggerFactory(out List<LogRecord> exportedItems, configure: o => o.IncludeFormattedMessage = includeFormattedMessage);
         var logger = loggerFactory.CreateLogger<LogRecordTests>();
+        var trufflePrice = 299.99;
 
         var food = new Dictionary<string, object>
         {
             ["Name"] = "truffle",
-            ["Price"] = 299.99,
+            ["Price"] = trufflePrice,
         };
         logger.Food(food);
 
@@ -276,16 +277,8 @@ public void CheckStateForStructuredLogWithGeneralType(bool includeFormattedMessa
         Assert.Equal("{Food}", exportedItems[0].Body);
         if (includeFormattedMessage)
         {
-            var prevCulture = CultureInfo.CurrentCulture;
-            CultureInfo.CurrentCulture = CultureInfo.InvariantCulture;
-            try
-            {
-                Assert.Equal("[Name, truffle], [Price, 299.99]", exportedItems[0].FormattedMessage);
-            }
-            finally
-            {
-                CultureInfo.CurrentCulture = prevCulture;
-            }
+            var priceInCurrentCulture = trufflePrice.ToString(CultureInfo.CurrentCulture);
+            Assert.Equal($"[Name, truffle], [Price, {priceInCurrentCulture}]", exportedItems[0].FormattedMessage);
         }
         else
         {