Aias00 opened a new pull request, #3547:
URL: https://github.com/apache/dubbo-go/pull/3547
## What
`handlePkg` serves many keep-alive requests in a `for` loop; each request
with a `Timeout` header created a `context.WithTimeout` whose `cancel` was
`defer`d **inside the loop**, so defers (and the retained contexts/timers)
accumulated for the connection's lifetime — a slow memory leak under sustained
keep-alive traffic.
## Why
```go
// protocol/jsonrpc/server.go handlePkg, per request in the for-loop (before)
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 (connection close), so each
keep-alive request with a `Timeout` header accumulates one deferred `cancel` +
retained context/timer. A persistent connection sending many timed requests
grows the defer chain unbounded → slow memory growth / eventual OOM. The `ctx`
is also not cancelled promptly after `serveRequest` returns.
## Fix
Call `cancel` explicitly after `serveRequest` returns (declared outside the
`if`):
```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 }
```
## Tests
Existing jsonrpc tests pass (the request-serving behavior is unchanged; the
fix is a scoped cancel-vs-defer change). A direct leak assertion isn't added
because defer accumulation isn't observable without a heap-profile harness; the
change is obviously correct (defer-in-loop → explicit call) and
behavior-preserving.
Fixes #3546
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