Merge pull request #115 from modelcontextprotocol/jerome/fix/clean-stdio-shutdown

Added clean shutdown + tests

Author: jerome3o-anthropic

src/integration-tests/process-cleanup.test.ts

@@ -0,0 +1,28 @@
+import { Server } from "../server/index.js";
+import { StdioServerTransport } from "../server/stdio.js";
+
+describe("Process cleanup", () => {
+  jest.setTimeout(5000); // 5 second timeout
+
+  it("should exit cleanly after closing transport", async () => {
+    const server = new Server(
+      {
+        name: "test-server",
+        version: "1.0.0",
+      },
+      {
+        capabilities: {},
+      }
+    );
+
+    const transport = new StdioServerTransport();
+    await server.connect(transport);
+
+    // Close the transport
+    await transport.close();
+
+    // If we reach here without hanging, the test passes
+    // The test runner will fail if the process hangs
+    expect(true).toBe(true);
+  });
+});

src/server/stdio.ts

@@ -62,8 +62,19 @@ export class StdioServerTransport implements Transport {
   }
 
   async close(): Promise<void> {
+    // Remove our event listeners first
     this._stdin.off("data", this._ondata);
     this._stdin.off("error", this._onerror);
+
+    // Check if we were the only data listener
+    const remainingDataListeners = this._stdin.listenerCount('data');
+    if (remainingDataListeners === 0) {
+      // Only pause stdin if we were the only listener
+      // This prevents interfering with other parts of the application that might be using stdin
+      this._stdin.pause();
+    }
+    
+    // Clear the buffer and notify closure
     this._readBuffer.clear();
     this.onclose?.();
   }