Stop buffering traces by default (dotnet#1645)

* Stop buffering the traces by default. * Don't modify stream buffering before we validate that we have a tracing file. Add test.
shangte · Jan 13, 2020 · 1c71a5f · 1c71a5f
1 parent 14db363
commit 1c71a5f
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diff --git a/src/installer/corehost/common/trace.cpp b/src/installer/corehost/common/trace.cpp
@@ -60,6 +60,7 @@ bool trace::enable()
 
             if (tracefile)
             {
+                setvbuf(tracefile, nullptr, _IONBF, 0);
                 g_trace_file = tracefile;
             }
             else

diff --git a/src/installer/test/HostActivation.Tests/NativeHosting/Nethost.cs b/src/installer/test/HostActivation.Tests/NativeHosting/Nethost.cs
@@ -240,6 +240,21 @@ public void GetHostFxrPath_InvalidParameters()
                 .And.HaveStdErrContaining("Invalid size for get_hostfxr_parameters");
         }
 
+        [Fact]
+        public void TracingNotBufferedByDefault()
+        {
+            CommandResult result = Command.Create(sharedState.NativeHostPath, $"{GetHostFxrPath} false nullptr x")
+                .EnvironmentVariable("COREHOST_TRACE", "1")
+                .EnvironmentVariable("COREHOST_TRACEFILE", "Tracing.out")
+                .MultilevelLookup(true)
+                .DotNetRoot(null)
+                .Execute();
+
+            result.Should().Fail()
+                .And.FileExists("Tracing.out")
+                .And.FileContains("Tracing.out", "Tracing enabled");
+        }
+
         [Fact]
         public void TestOnlyDisabledByDefault()
         {
-Original file line number
+Diff line change
@@ Expand Up / @@ -60,6 +60,7 @@ bool trace::enable() @@
                 if (tracefile)
                 {
+                    setvbuf(tracefile, nullptr, _IONBF, 0);
                     g_trace_file = tracefile;
                 }
                 else
@@ Expand Down @@