ci: harden exec-mode test against macOS connection races#63
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The exec suite opens many short-lived SSH connections in quick succession. On macOS CI the closed sockets linger, so the default per-IP concurrency cap (5) is transiently exceeded and a connection is refused mid-suite, producing a flaky 'users usage output unexpected' failure (seen on PR #62; the same test passes on Ubuntu and locally). Raise the test server's per-IP/global connection caps well above the in-flight count this suite can produce, and add ssh ConnectionAttempts/ ConnectTimeout so a dropped identification handshake is retried rather than failing the assertion. Verified stable across repeated local macOS runs.
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Problem
test_exec_mode.shintermittently fails only on the macOS CI runner with✗ users usage output unexpected(observed on PR #62). The same test passes on Ubuntu CI and locally on macOS.Root cause
The suite opens many short-lived SSH exec connections in quick succession. On macOS the closed sockets linger (TIME_WAIT), so the server's default per-IP concurrency cap (
TNT_DEFAULT_MAX_CONN_PER_IP = 5) is transiently exceeded and a connection is refused mid-suite → empty output → the usagegrepfails. The test disabled the rate limit (TNT_RATE_LIMIT=0) but not the concurrency cap.Fix
TNT_MAX_CONN_PER_IP=256 TNT_MAX_CONNECTIONS=256(well above the in-flight count this suite produces).-o ConnectionAttempts=3 -o ConnectTimeout=15to the test'sSSH_OPTSso a dropped identification handshake is retried rather than failing the assertion.No product code changes; test-only. Verified stable across repeated local macOS runs (25/25 each).