Check for pending IO in the portable thread pool's worker threads (#82245)

* Check for pending IO in the portable thread pool's worker threads

- When Resource Monitor is attached, some async IO operations are bound to the thread that issued it even though the IO handle is bound to an IOCP. If the thread exits, the async IO operation is aborted. This can lead to hangs or unexpected exceptions.
- Added a check that was missing in the portable thread pool implementation to prevent exiting a worker thread when it has pending IO

Fixes https://github.com/dotnet/runtime/issues/82207

diff --git a/src/libraries/Common/src/Interop/Windows/Kernel32/Interop.Threading.cs b/src/libraries/Common/src/Interop/Windows/Kernel32/Interop.Threading.cs
index f64a23f..9a53b48 100644 (file)
--- a/src/libraries/Common/src/Interop/Windows/Kernel32/Interop.Threading.cs
+++ b/src/libraries/Common/src/Interop/Windows/Kernel32/Interop.Threading.cs
@@ -70,5 +70,9 @@ internal static partial class Interop
         [LibraryImport(Libraries.Kernel32)]
         [return:MarshalAs(UnmanagedType.Bool)]
         internal static partial bool SetThreadPriority(SafeWaitHandle hThread, int nPriority);
+
+        [LibraryImport(Libraries.Kernel32, SetLastError = true)]
+        [return: MarshalAs(UnmanagedType.Bool)]
+        internal static partial bool GetThreadIOPendingFlag(nint hThread, out BOOL lpIOIsPending);
     }
 }

diff --git a/src/libraries/System.Private.CoreLib/src/System.Private.CoreLib.Shared.projitems b/src/libraries/System.Private.CoreLib/src/System.Private.CoreLib.Shared.projitems
index bbef0e9..b200e12 100644 (file)
--- a/src/libraries/System.Private.CoreLib/src/System.Private.CoreLib.Shared.projitems
+++ b/src/libraries/System.Private.CoreLib/src/System.Private.CoreLib.Shared.projitems
@@ -1854,6 +1854,9 @@
     <Compile Include="$(CommonPath)Interop\Windows\Kernel32\Interop.SystemTimeToFileTime.cs">
       <Link>Common\Interop\Windows\Kernel32\Interop.SystemTimeToFileTime.cs</Link>
     </Compile>
+    <Compile Include="$(CommonPath)Interop\Windows\Kernel32\Interop.Threading.cs">
+      <Link>Common\Interop\Windows\Kernel32\Interop.Threading.cs</Link>
+    </Compile>
     <Compile Include="$(CommonPath)Interop\Windows\Kernel32\Interop.TimeZone.cs">
       <Link>Common\Interop\Windows\Kernel32\Interop.TimeZone.cs</Link>
     </Compile>
@@ -2502,8 +2505,8 @@
     <Compile Include="$(MSBuildThisFileDirectory)System\Threading\PortableThreadPool.WaitThread.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Threading\PortableThreadPool.WorkerThread.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Threading\PortableThreadPool.WorkerTracking.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)System\Threading\PortableThreadPool.CpuUtilizationReader.Unix.cs" Condition="'$(TargetsUnix)' == 'true' or '$(TargetsBrowser)' == 'true' or '$(TargetsWasi)' == 'true'" />
-    <Compile Include="$(MSBuildThisFileDirectory)System\Threading\PortableThreadPool.CpuUtilizationReader.Windows.cs" Condition="'$(TargetsWindows)' == 'true'" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Threading\PortableThreadPool.Unix.cs" Condition="'$(TargetsUnix)' == 'true' or '$(TargetsBrowser)' == 'true' or '$(TargetsWasi)' == 'true'" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Threading\PortableThreadPool.Windows.cs" Condition="'$(TargetsWindows)' == 'true'" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Threading\LowLevelLifoSemaphore.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Threading\LowLevelLifoSemaphore.Windows.cs" Condition="'$(TargetsWindows)' == 'true'" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Threading\PreAllocatedOverlapped.cs" Condition="('$(TargetsBrowser)' != 'true' and '$(TargetsWasi)' != 'true') or '$(FeatureWasmThreads)' == 'true'" />
@@ -2537,9 +2540,6 @@
   </ItemGroup>
   <ItemGroup Condition="'$(FeatureCoreCLR)' != 'true' and '$(TargetsWindows)' == 'true'">
     <Compile Include="$(MSBuildThisFileDirectory)System\Threading\WaitHandle.Windows.cs" />
-    <Compile Include="$(CommonPath)\Interop\Windows\Kernel32\Interop.Threading.cs">
-      <Link>Interop\Windows\Kernel32\Interop.Threading.cs</Link>
-    </Compile>
   </ItemGroup>
   <ItemGroup>
     <Compile Include="$(MSBuildThisFileDirectory)System\IParsable.cs" />

diff --git a/src/libraries/System.Private.CoreLib/src/System/Threading/PortableThreadPool.CpuUtilizationReader.Unix.cs b/src/libraries/System.Private.CoreLib/src/System/Threading/PortableThreadPool.Unix.cs
similarity index 80%
rename from src/libraries/System.Private.CoreLib/src/System/Threading/PortableThreadPool.CpuUtilizationReader.Unix.cs
rename to src/libraries/System.Private.CoreLib/src/System/Threading/PortableThreadPool.Unix.cs
index ea754f9..100ddf0 100644 (file)
--- a/src/libraries/System.Private.CoreLib/src/System/Threading/PortableThreadPool.CpuUtilizationReader.Unix.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/Threading/PortableThreadPool.Unix.cs
@@ -5,6 +5,11 @@ namespace System.Threading
 {
     internal sealed partial class PortableThreadPool
     {
+        private static partial class WorkerThread
+        {
+            private static bool IsIOPending => false;
+        }
+
         private struct CpuUtilizationReader
         {
             private Interop.Sys.ProcessCpuInformation _cpuInfo;

diff --git a/src/libraries/System.Private.CoreLib/src/System/Threading/PortableThreadPool.CpuUtilizationReader.Windows.cs b/src/libraries/System.Private.CoreLib/src/System/Threading/PortableThreadPool.Windows.cs
similarity index 75%
rename from src/libraries/System.Private.CoreLib/src/System/Threading/PortableThreadPool.CpuUtilizationReader.Windows.cs
rename to src/libraries/System.Private.CoreLib/src/System/Threading/PortableThreadPool.Windows.cs
index 4818512..6f5d7ef 100644 (file)
--- a/src/libraries/System.Private.CoreLib/src/System/Threading/PortableThreadPool.CpuUtilizationReader.Windows.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/Threading/PortableThreadPool.Windows.cs
@@ -8,6 +8,20 @@ namespace System.Threading
 {
     internal sealed partial class PortableThreadPool
     {
+        private static partial class WorkerThread
+        {
+            private static bool IsIOPending
+            {
+                get
+                {
+                    bool success =
+                        Interop.Kernel32.GetThreadIOPendingFlag(Interop.Kernel32.GetCurrentThread(), out Interop.BOOL isIOPending);
+                    Debug.Assert(success);
+                    return !success || isIOPending != Interop.BOOL.FALSE;
+                }
+            }
+        }
+
         private struct CpuUtilizationReader
         {
             public long _idleTime;

diff --git a/src/libraries/System.Private.CoreLib/src/System/Threading/PortableThreadPool.WorkerThread.cs b/src/libraries/System.Private.CoreLib/src/System/Threading/PortableThreadPool.WorkerThread.cs
index 0e0323e..96578b9 100644 (file)
--- a/src/libraries/System.Private.CoreLib/src/System/Threading/PortableThreadPool.WorkerThread.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/Threading/PortableThreadPool.WorkerThread.cs
@@ -10,7 +10,7 @@ namespace System.Threading
         /// <summary>
         /// The worker thread infastructure for the CLR thread pool.
         /// </summary>
-        private static class WorkerThread
+        private static partial class WorkerThread
         {
             private const int SemaphoreSpinCountDefaultBaseline = 70;
 #if !TARGET_ARM64 && !TARGET_ARM && !TARGET_LOONGARCH64
@@ -115,6 +115,12 @@ namespace System.Threading
                         }
                     }
 
+                    // The thread cannot exit if it has IO pending, otherwise the IO may be canceled
+                    if (IsIOPending)
+                    {
+                        continue;
+                    }
+
                     threadAdjustmentLock.Acquire();
                     try
                     {