The StdioClientTransport.close() method doesn't properly terminate spawned child processes, causing
memory leaks in applications that frequently connect/disconnect from STDIO MCP servers.
In client/stdio.js, the close() method only aborts the spawn signal and nullifies the process
reference, but doesn't actually kill the running child process:
asyncclose(){this._abortController.abort();// Only prevents new spawnsthis._process=undefined;// Just removes referencethis._readBuffer.clear();}To Reproduce
FOR 1000 times:
transport = new StdioClientTransport(server_command)
client = new Client()
client.connect(transport) // spawns child process
pid = transport.pid
client.close() // BUG: doesn't kill child process
// Process with 'pid' is still running (memory leak)
// Result: 1000 orphaned processes still running
Expected behavior
When close() is called, the spawned child process should be terminated to prevent resource leaks.
The
StdioClientTransport.close()method doesn't properly terminate spawned child processes, causingmemory leaks in applications that frequently connect/disconnect from STDIO MCP servers.
In
client/stdio.js, theclose()method only aborts the spawn signal and nullifies the processreference, but doesn't actually kill the running child process:
To Reproduce
Expected behavior
When close() is called, the spawned child process should be terminated to prevent resource leaks.