fix: cleanup zombie processes for child process client (#156)

* feat(client): cleanup of zombie processes in child process client

Using process wrap library, Process Group for Unix and Job Object for Windows

* fix: install extra dep based on feature, update examples take owned command

Install process-wrap if transport-child-process feature is enabled. Update examples to take ownership
of the command instead of mutable reference

* fix: update other examples, comments and readme to take ownership of command

Updated more examples, comments and readme to take command instead of mutable ref.
Also small fix in cargo toml of example to use local path.

* refactor: add configure command ext

Added configure command ext to tokio process command so that
you can use .configure() to use inline commands for mcp stdio client.
Added warning if start kill process fails

examples/clients/src/collection.rs

@@ -1,7 +1,11 @@
 use std::collections::HashMap;
 
 use anyhow::Result;
-use rmcp::{model::CallToolRequestParam, service::ServiceExt, transport::TokioChildProcess};
+use rmcp::{
+    model::CallToolRequestParam,
+    service::ServiceExt,
+    transport::{ConfigureCommandExt, TokioChildProcess},
+};
 use tokio::process::Command;
 use tracing_subscriber::{layer::SubscriberExt, util::SubscriberInitExt};
 
@@ -20,9 +24,11 @@ async fn main() -> Result<()> {
     for idx in 0..10 {
         let service = ()
             .into_dyn()
-            .serve(TokioChildProcess::new(
-                Command::new("uvx").arg("mcp-server-git"),
-            )?)
+            .serve(TokioChildProcess::new(Command::new("uvx").configure(
+                |cmd| {
+                    cmd.arg("mcp-client-git");
+                },
+            ))?)
             .await?;
         client_list.insert(idx, service);
     }

examples/clients/src/everything_stdio.rs

@@ -3,7 +3,7 @@ use rmcp::{
     ServiceExt,
     model::{CallToolRequestParam, GetPromptRequestParam, ReadResourceRequestParam},
     object,
-    transport::TokioChildProcess,
+    transport::{ConfigureCommandExt, TokioChildProcess},
 };
 use tokio::process::Command;
 use tracing_subscriber::{layer::SubscriberExt, util::SubscriberInitExt};
@@ -21,11 +21,11 @@ async fn main() -> Result<()> {
 
     // Start server
     let service = ()
-        .serve(TokioChildProcess::new(
-            Command::new("npx")
-                .arg("-y")
-                .arg("@modelcontextprotocol/server-everything"),
-        )?)
+        .serve(TokioChildProcess::new(Command::new("npx").configure(
+            |cmd| {
+                cmd.arg("-y").arg("@modelcontextprotocol/server-everything");
+            },
+        ))?)
         .await?;
 
     // Initialize

examples/clients/src/std_io.rs

@@ -1,5 +1,9 @@
 use anyhow::Result;
-use rmcp::{model::CallToolRequestParam, service::ServiceExt, transport::TokioChildProcess};
+use rmcp::{
+    model::CallToolRequestParam,
+    service::ServiceExt,
+    transport::{ConfigureCommandExt, TokioChildProcess},
+};
 use tokio::process::Command;
 use tracing_subscriber::{layer::SubscriberExt, util::SubscriberInitExt};
 
@@ -14,17 +18,14 @@ async fn main() -> Result<()> {
         .with(tracing_subscriber::fmt::layer())
         .init();
     let service = ()
-        .serve(TokioChildProcess::new(
-            Command::new("uvx").arg("mcp-server-git"),
-        )?)
+        .serve(TokioChildProcess::new(Command::new("uvx").configure(
+            |cmd| {
+                cmd.arg("mcp-server-git");
+            },
+        ))?)
         .await?;
 
-    // or
-    // serve_client(
-    //     (),
-    //     TokioChildProcess::new(Command::new("uvx").arg("mcp-server-git"))?,
-    // )
-    // .await?;
+    // or serve_client((), TokioChildProcess::new(cmd)?).await?;
 
     // Initialize
     let server_info = service.peer_info();

examples/rig-integration/src/config/mcp.rs

@@ -1,6 +1,6 @@
 use std::{collections::HashMap, process::Stdio};
 
-use rmcp::{RoleClient, ServiceExt, service::RunningService};
+use rmcp::{RoleClient, ServiceExt, service::RunningService, transport::ConfigureCommandExt};
 use serde::{Deserialize, Serialize};
 
 use crate::mcp_adaptor::McpManager;
@@ -70,10 +70,9 @@ impl McpServerTransportConfig {
                 envs,
             } => {
                 let transport = rmcp::transport::TokioChildProcess::new(
-                    tokio::process::Command::new(command)
-                        .args(args)
-                        .envs(envs)
-                        .stderr(Stdio::null()),
+                    tokio::process::Command::new(command).configure(|cmd| {
+                        cmd.args(args).envs(envs).stderr(Stdio::null());
+                    }),
                 )?;
                 ().serve(transport).await?
             }

examples/simple-chat-client/src/config.rs

@@ -1,7 +1,7 @@
 use std::{collections::HashMap, path::Path, process::Stdio};
 
 use anyhow::Result;
-use rmcp::{RoleClient, ServiceExt, service::RunningService};
+use rmcp::{RoleClient, ServiceExt, service::RunningService, transport::ConfigureCommandExt};
 use serde::{Deserialize, Serialize};
 
 #[derive(Debug, Serialize, Deserialize)]
@@ -55,11 +55,12 @@ impl McpServerTransportConfig {
                 envs,
             } => {
                 let transport = rmcp::transport::child_process::TokioChildProcess::new(
-                    tokio::process::Command::new(command)
-                        .args(args)
-                        .envs(envs)
-                        .stderr(Stdio::inherit())
-                        .stdout(Stdio::inherit()),
+                    tokio::process::Command::new(command).configure(|cmd| {
+                        cmd.args(args)
+                            .envs(envs)
+                            .stderr(Stdio::inherit())
+                            .stdout(Stdio::inherit());
+                    }),
                 )?;
                 ().serve(transport).await?
             }