[I] [BUG] jsonrpc: defer cancel() inside per-connection request loop leaks contexts for keep-alive connections [dubbo-go]

["Aias00 (via GitHub)" <gi...@apache.org>]

Aias00 opened a new issue, #3546:
URL: https://github.com/apache/dubbo-go/issues/3546

   ### Problem
   
   `protocol/jsonrpc/server.go` `handlePkg` runs for the lifetime of one keep-alive TCP connection and serves many HTTP requests in a `for` loop. Each request carrying a `Timeout` header creates a `context.WithTimeout` whose `cancel` is `defer`red **inside the loop**:
   
   ```go
   // protocol/jsonrpc/server.go handlePkg, per request in the for-loop
   if len(reqHeader["Timeout"]) > 0 {
       timeout, err := time.ParseDuration(reqHeader["Timeout"])
       if err == nil {
           httpTimeout = timeout
           var cancel context.CancelFunc
           ctx, cancel = context.WithTimeout(ctx, httpTimeout)
           defer cancel()   // <-- defer inside a loop, in a long-lived fn
       }
       delete(reqHeader, "Timeout")
   }
   ```
   
   `defer` only runs when `handlePkg` returns (i.e. when the connection closes), so each keep-alive request with a `Timeout` header accumulates one deferred `cancel` + its retained context (and the canceler/timer) in the connection goroutine until the connection tears down.
   
   ### Current behavior
   
   A client opens a persistent/keep-alive connection and sends many requests each with a `Timeout` header. Each request accumulates one deferred `cancel` + retained context in the connection goroutine → unbounded growth of the defer chain and retained context objects → slow memory growth / eventual OOM under sustained keep-alive traffic. The `ctx` is also not cancelled promptly after `serveRequest` returns (the timer holds resources until it fires or the connection closes).
   
   ### Expected behavior
   
   The timeout context should be cancelled promptly after `serveRequest` returns for that request, with no accumulation across the keep-alive connection.
   
   ### Suggested approach
   
   Replace `defer cancel()` (inside the loop) with an explicit `cancel()` call after `serveRequest` returns:
   
   ```go
   var cancel context.CancelFunc
   if len(reqHeader["Timeout"]) > 0 {
       timeout, err := time.ParseDuration(reqHeader["Timeout"])
       if err == nil {
           httpTimeout = timeout
           ctx, cancel = context.WithTimeout(ctx, httpTimeout)
       }
       delete(reqHeader, "Timeout")
   }
   setTimeout(conn, httpTimeout)
   
   serveErr := serveRequest(ctx, reqHeader, reqBody, conn)
   if cancel != nil { cancel() }
   if serveErr != nil { ... return }
   ```
   
   ### Acceptance criteria
   
   - [ ] No `defer` accumulates per request in the `handlePkg` loop.
   - [ ] The timeout context is cancelled after `serveRequest` returns.
   - [ ] Existing jsonrpc tests remain green.
   


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Re: [I] [BUG] jsonrpc: defer cancel() inside per-connection request loop leaks contexts for keep-alive connections [dubbo-go]

["Alanxtl (via GitHub)" <gi...@apache.org>]

Alanxtl commented on issue #3546:
URL: https://github.com/apache/dubbo-go/issues/3546#issuecomment-5086259572

   not planned


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Re: [I] [BUG] jsonrpc: defer cancel() inside per-connection request loop leaks contexts for keep-alive connections [dubbo-go]

["Alanxtl (via GitHub)" <gi...@apache.org>]

Alanxtl closed issue #3546: [BUG] jsonrpc: defer cancel() inside per-connection request loop leaks contexts for keep-alive connections
URL: https://github.com/apache/dubbo-go/issues/3546


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