Hacktoberfest 2026: the issues maintainers tagged for October, open and beginner-friendly. Browse Hacktoberfest issues

io.modelcontextprotocol.client.transport.StdioClientTransport#closeGracefully

Open
#496 2 comments 0 reactions 0 assignees View on GitHub

Nobody has claimed this yet.

Assessment

Difficulty
3/5
Estimated time
1-2 days
Newbie friendliness
55/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Quiet
Tech stack
java, node.js
Domain
backend, operating-systems

Research direction

Start at io.modelcontextprotocol.client.transport.StdioClientTransport#closeGracefully and reproduce the Windows npx.cmd example from the issue. Investigate how the launched process and its child processes are terminated; done means closing the client also ends the subprocess tree and the main method can return normally.

Written by the indexing model from the issue text.

Description

area/client enhancement P2 ready for work

Bug description
When npx is launched on Windows, a related subprocess is initiated. When using the io.modelcontextprotocol.client.transport.StdioClientTransport#closeGracefully method to close, this.process.destroy() will only terminate the current process, but the subprocess cannot be closed, resulting in the main method not being able to end normally. Therefore, the taskkill pid /F /T command needs to be used to terminate it.

Environment
jdk 17
mcp 0.12.0-SNAPSHOT
windows 11
Steps to reproduce
StdioClientTransport stdioClientTransport = new StdioClientTransport(ServerParameters.builder("D:\dev\nodejs\npx.cmd").args(Arrays.asList("-y","@wopal/mcp-server-hotnews")).build());
McpSyncClient mcpClient = McpClient.sync(stdioClientTransport)
.requestTimeout(Duration.ofSeconds(20L))
.capabilities(McpSchema.ClientCapabilities.builder()
.roots(true)
.sampling()
.build())
.build();
mcpClient.initialize();
McpSchema.ListToolsResult listToolsResult = mcpClient.listTools();
List<McpSchema.Tool> tools = listToolsResult.tools();
System.out.println(tools.get(0).name());
mcpClient.closeGracefully();

Expected behavior
Close the child processes simultaneously

Minimal Complete Reproducible example
StdioClientTransport stdioClientTransport = new StdioClientTransport(ServerParameters.builder("D:\dev\nodejs\npx.cmd").args(Arrays.asList("-y","@wopal/mcp-server-hotnews")).build());
McpSyncClient mcpClient = McpClient.sync(stdioClientTransport)
.requestTimeout(Duration.ofSeconds(20L))
.capabilities(McpSchema.ClientCapabilities.builder()
.roots(true)
.sampling()
.build())
.build();
mcpClient.initialize();
McpSchema.ListToolsResult listToolsResult = mcpClient.listTools();
List<McpSchema.Tool> tools = listToolsResult.tools();
System.out.println(tools.get(0).name());
mcpClient.closeGracefully();

Image
Dominant language
Java
Stars
3.7k
Forks
1.1k
Avg merge
1d 15h
Merged PRs (30d)
9

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

More from modelcontextprotocol/java-sdk

All issues in modelcontextprotocol/java-sdk

Similar issues

More Java issues

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.