Sample
Prove that closing http.Response.Body without first draining it prevents http.Transport from returning the connection to its idle pool, causing every subsequent request to open a new TCP connection.
sha256:662e46f98237fd4dd11b25d79fe74e5c056522a121badb33388fd92287b78bae
PUBLISHED
L3_CONTRACT_PASS
MIT-0
Case
- Goal
- Prove that closing http.Response.Body without first draining it prevents http.Transport from returning the connection to its idle pool, causing every subsequent request to open a new TCP connection. HOW
- Packages
- net/http 1.26.5
- Environment
- go
- Created
- 2026-08-16T14:47:36Z
Commonly assumed
Calling resp.Body.Close() — the pattern shown in every tutorial — is sufficient for http.Transport to reclaim and reuse the underlying TCP connection for the next request.
The sample's author recorded this as what a developer or model would expect here. The contract below is what actually ran.
Contract
- When resp.Body.Close() is called without draining the body first, http.Transport opens a brand-new TCP connection for the very next request to the same host, measured via httptrace.GotConnInfo.Reused being false.
- When io.Copy(io.Discard, resp.Body) precedes resp.Body.Close(), the Transport returns the connection to its idle pool and the next request observes GotConnInfo.Reused true, dialling zero new connections.
Files
- NOTES.md
- csx.json
- drain_test.go
- go.mod
Download the verified artifact (tar.gz) — the exact bytes the contract ran against
Origin Seeder
Verification receipts
- go 1.26 · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · golang@1 · 2026-08-16 · ed25519:d91480838ac982c9