Concurrent requests overwrite each other's instrumentation data

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@atesgoral 已經在處理了。

開始於 2026年11月6日。

  • #668 來自 @atesgoral —— 未關閉

評估

難度
3/5
預估耗時
1-2 天
新手友好度
35/100
Issue 類型
缺陷
描述清晰度
描述清楚
活躍度
停滯
技術堆疊
ruby

研究方向

Start with lib/mcp/instrumentation.rb, especially instrument_call and add_instrumentation_data, then read the concurrent shared server test in test/mcp/server_test.rb and the tool call instrumentation in lib/mcp/server.rb. Reproduce the interleaving described in the issue and check how request data reaches the callback; done when concurrent requests produce separate records with the correct tool names. An open pull request (#668) is already addressing this issue.

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描述

bug

Instrumentation#instrument_call keeps the per-request record in @instrumentation_data, an instance variable on the shared Server (instrumentation.rb:8). When two requests run at the same time on one server, for example Streamable HTTP on a threaded Rack server, the second request replaces the hash.

The first request then writes its later fields (client, error, duration) into the second request's hash and passes that hash to instrumentation_callback (instrumentation.rb:43, :48). The first request's own record, with its tool_name and tool_arguments (server.rb:1408), is never sent to the callback. around_request gets the original hash (instrumentation.rb:17) but misses the fields written after the swap.

Concurrent use of one server is supported (see test "#handle concurrent requests on a shared server report exceptions independently" in test/mcp/server_test.rb).

Repro

Run from the repository root with bundle exec ruby -I lib repro.rb:

require "mcp"

entered = Queue.new
release = Queue.new
slow_tool = MCP::Tool.define(name: "slow_tool") do
  entered << true
  release.pop
  MCP::Tool::Response.new([{ type: "text", text: "slow" }])
end
fast_tool = MCP::Tool.define(name: "fast_tool") do
  MCP::Tool::Response.new([{ type: "text", text: "fast" }])
end

records = Queue.new
configuration = MCP::Configuration.new
configuration.instrumentation_callback = ->(data) { records << data.dup }
server = MCP::Server.new(name: "example", tools: [slow_tool, fast_tool], configuration: configuration)

call = ->(id, name) { server.handle({ jsonrpc: "2.0", id: id, method: "tools/call", params: { name: name, arguments: {} } }) }
thread = Thread.new { call.call(1, "slow_tool") }
entered.pop
call.call(2, "fast_tool")
release << true
thread.join

p(2.times.map { records.pop[:tool_name] })

Expected: ["fast_tool", "slow_tool"]

Actual: ["fast_tool", "fast_tool"]

Suggested fix

Keep the record local to the request instead of on the shared server. For example, create the hash in instrument_call and pass it to add_instrumentation_data, or keep it in a fiber-local value that instrument_call sets and restores.

主要語言
Ruby
星號
940
分支
143
平均合併
1 天 5 小時
30 天內合併 PR
48

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  3. Fork 儲存庫,在一個分支上完成修改。
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