Use Process.Kill(entireProcessTree: true) on .NET for faster process termination (#1187)

Author: stephentoub

src/ModelContextProtocol.Core/ProcessHelper.cs

@@ -8,36 +8,25 @@ namespace ModelContextProtocol;
 /// </summary>
 internal static class ProcessHelper
 {
-    private static readonly bool _isWindows = RuntimeInformation.IsOSPlatform(OSPlatform.Windows);
-    private static readonly TimeSpan _defaultTimeout = TimeSpan.FromSeconds(30);
-
-    /// <summary>
-    /// Kills a process and all of its child processes (entire process tree).
-    /// </summary>
-    /// <param name="process">The process to terminate along with its child processes.</param>
-    /// <remarks>
-    /// This method uses a default timeout of 30 seconds when waiting for processes to exit.
-    /// On Windows, this uses the "taskkill" command with the /T flag.
-    /// On non-Windows platforms, it recursively identifies and terminates child processes.
-    /// </remarks>
-    public static void KillTree(this Process process) => process.KillTree(_defaultTimeout);
-
     /// <summary>
     /// Kills a process and all of its child processes (entire process tree) with a specified timeout.
     /// </summary>
     /// <param name="process">The process to terminate along with its child processes.</param>
     /// <param name="timeout">The maximum time to wait for the processes to exit.</param>
     /// <remarks>
-    /// On Windows, this uses the "taskkill" command with the /T flag to terminate the process tree.
-    /// On non-Windows platforms, it recursively identifies and terminates child processes.
+    /// On .NET Core 3.0+ this uses <c>Process.Kill(entireProcessTree: true)</c>.
+    /// On .NET Standard 2.0, it uses platform-specific commands (taskkill on Windows, pgrep/kill on Unix).
     /// The method waits for the specified timeout for processes to exit before continuing.
     /// This is particularly useful for applications that spawn child processes (like Node.js)
     /// that wouldn't be terminated automatically when the parent process exits.
     /// </remarks>
     public static void KillTree(this Process process, TimeSpan timeout)
     {
+#if NETSTANDARD2_0
+        // Process.Kill(entireProcessTree) is not available on .NET Standard 2.0.
+        // Use platform-specific commands to kill the process tree.
         var pid = process.Id;
-        if (_isWindows)
+        if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
         {
             RunProcessAndWaitForExit(
                 "taskkill",
@@ -53,50 +42,50 @@ public static void KillTree(this Process process, TimeSpan timeout)
             {
                 KillProcessUnix(childId, timeout);
             }
+
             KillProcessUnix(pid, timeout);
         }
+#else
+        try
+        {
+            process.Kill(entireProcessTree: true);
+        }
+        catch
+        {
+            // Process has already exited
+            return;
+        }
+#endif
 
         // wait until the process finishes exiting/getting killed. 
         // We don't want to wait forever here because the task is already supposed to be dieing, we just want to give it long enough
         // to try and flush what it can and stop. If it cannot do that in a reasonable time frame then we will just ignore it.
         process.WaitForExit((int)timeout.TotalMilliseconds);
     }
 
+#if NETSTANDARD2_0
     private static void GetAllChildIdsUnix(int parentId, ISet<int> children, TimeSpan timeout)
     {
-        var exitcode = RunProcessAndWaitForExit(
-            "pgrep",
-            $"-P {parentId}",
-            timeout,
-            out var stdout);
+        int exitcode = RunProcessAndWaitForExit("pgrep", $"-P {parentId}", timeout, out var stdout);
 
         if (exitcode == 0 && !string.IsNullOrEmpty(stdout))
         {
             using var reader = new StringReader(stdout);
-            while (true)
+            while (reader.ReadLine() is string text)
             {
-                var text = reader.ReadLine();
-                if (text == null)
-                    return;
-
                 if (int.TryParse(text, out var id))
                 {
                     children.Add(id);
+
                     // Recursively get the children
                     GetAllChildIdsUnix(id, children, timeout);
                 }
             }
         }
     }
 
-    private static void KillProcessUnix(int processId, TimeSpan timeout)
-    {
-        RunProcessAndWaitForExit(
-            "kill",
-            $"-TERM {processId}",
-            timeout,
-            out var _);
-    }
+    private static void KillProcessUnix(int processId, TimeSpan timeout) =>
+        RunProcessAndWaitForExit("kill", $"-TERM {processId}", timeout, out _);
 
     private static int RunProcessAndWaitForExit(string fileName, string arguments, TimeSpan timeout, out string? stdout)
     {
@@ -112,19 +101,21 @@ private static int RunProcessAndWaitForExit(string fileName, string arguments, T
 
         stdout = null;
 
-        var process = Process.Start(startInfo);
-        if (process == null)
-            return -1;
-
-        if (process.WaitForExit((int)timeout.TotalMilliseconds))
-        {
-            stdout = process.StandardOutput.ReadToEnd();
-        }
-        else
+        if (Process.Start(startInfo) is { } process)
         {
-            process.Kill();
+            if (process.WaitForExit((int)timeout.TotalMilliseconds))
+            {
+                stdout = process.StandardOutput.ReadToEnd();
+            }
+            else
+            {
+                process.Kill();
+            }
+
+            return process.ExitCode;
         }
 
-        return process.ExitCode;
+        return -1;
     }
+#endif
 }