jpmschweitzerandClaude Opus 4.8
9c288a618b
Verification tooling for the Windows freeze assessment (T-424). provision-vm.sh stands up a Windows KVM guest (dry-run unless --go); bootstrap-windows.ps1 installs Flutter + VS C++ Build Tools and checks out the branch; soak-conpty.ps1 runs the pty suite in a fresh dart.exe per iteration and measures the orphaned conhost/cmd count that survives each exit (the leak signature), with a per-iteration timeout so a wedged test can't stall the run. Verifies the ConPTY leak (#1-#4); the GPU/TDR hypothesis (#5) needs passthrough/bare metal (README appendix). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
87 lines
4.6 KiB
Markdown
87 lines
4.6 KiB
Markdown
# windows-verify — ConPTY leak verification kit
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Tooling to **verify (or refute) the Windows test-freeze assessment** for the
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`windows-support` branch on a real Windows VM. See the full analysis in
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`docs/windows-freeze-analysis.md` (or the report shared in the session).
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> **Status: nothing here runs automatically.** These scripts are inert until
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> you invoke them. `provision-vm.sh` is a **dry run** unless you pass `--go`.
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## What this verifies — and what it can't
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| Hypothesis | In scope here? | Why |
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| **#1** orphaned `conhost.exe`/`cmd.exe` accumulation (no Job Object) | **✅ yes** | `soak-conpty.ps1` measures the orphan count directly — this is the headline result. |
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| **#2** unkillable blocked-FFI isolate threads | ✅ partial | Per-run `dart.exe` peak handle/thread footprint is sampled; the leak is reclaimed at process exit, so it shows as a *within-run* spike, not cross-run growth. |
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| **#3** narrow-terminal CRLF conhost spin | ⚠️ manual | Surfaces as a host that pegs a CPU core; watch Task Manager during a soak. The real fix is clamping `cols/rows ≥ 2` + a unit test. |
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| **#4** `ClosePseudoConsole` hang (pre-24H2) | ⚠️ partial | Run on a **pre-24H2** image (build < 26100) *and* a 24H2+ image to see the version-gated intermittency. |
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| **#5** GPU/display-driver TDR (`0x116`) — the real black-screen | **❌ no** | A stock VM uses a software (WARP) adapter; `make run` cannot trigger a hardware TDR. Needs GPU passthrough or bare metal — see the appendix. |
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The leak (#1) is the **test-path** explanation and the actionable one. A VM is
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the right instrument for it; it is the wrong instrument for #5.
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## The three steps
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1. **Provision the VM** (on the Fedora/KVM host — "danoontje"):
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```bash
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WIN_ISO=~/iso/Win11.iso VIRTIO_ISO=~/iso/virtio-win.iso \
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tools/windows-verify/provision-vm.sh # dry run — prints the plan
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WIN_ISO=... VIRTIO_ISO=... tools/windows-verify/provision-vm.sh --go # execute
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```
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Finish the interactive Windows install in `virt-viewer` (load the virtio
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disk driver from the second CD during setup).
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2. **Bootstrap the toolchain** (inside Windows, elevated PowerShell):
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```powershell
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pwsh -File tools\windows-verify\bootstrap-windows.ps1
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```
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Installs Git, Flutter/Dart, and VS 2022 Build Tools (C++ workload), then
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clones + checks out `windows-support` and builds the C CLI.
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3. **Run the soak** (new shell, so PATH is fresh):
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```powershell
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pwsh -File tools\windows-verify\soak-conpty.ps1 -Iterations 40
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```
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## Reading the result
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`soak-conpty.ps1` runs the ConPTY suite in a **fresh `dart.exe` per
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iteration** and, after each one exits, counts the `conhost`/`OpenConsole`/`cmd`
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processes that **survived** (baseline-subtracted). It writes a per-iteration
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CSV + a summary to `%LOCALAPPDATA%\clide\windows-verify\` (flushed each line,
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so the data survives even if a later run wedges the box).
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- **Orphan count climbs and stays up** (e.g. +1 per iteration, never reclaimed)
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→ **leak confirmed (#1)**: ConPTY hosts outlive the test process. This is the
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cumulative starvation that, across many runs, thrashes the session to a
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power-cycle.
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- **Orphan count hovers at ~0** → not reproduced in this config (more
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iterations may be needed, or the Job-Object fix is already in place).
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- **`dart_peak_handles`/`threads` ratchet up *within* a run** → corroborates #2
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(blocked reader/waiter isolates), reclaimed when `dart.exe` exits.
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The script never tries to crash the machine — it proves the *mechanism* (an
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unreclaimed, monotonically growing host population), which is the safe and
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sufficient verification.
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## Safety notes
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- Snapshot the VM before soaking (`virsh snapshot-create-as clide-win-verify clean`)
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so you can roll back instead of reinstalling.
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- If hosts strand after a run: `Get-Process conhost,OpenConsole,cmd | Stop-Process -Force`.
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- Do this in a VM, not a machine you care about — the whole point is to provoke
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a resource leak.
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## Appendix — chasing the GPU/TDR hypothesis (#5)
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A software-rendered VM can't reproduce a real display-driver TDR. To test #5
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you need **GPU passthrough** (bind the GPU to `vfio-pci`, pass it with
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`--hostdev`, install the vendor WDDM driver in the guest) or, more simply, run
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`make run` / `make run-testmode` on the **bare-metal Windows box** that
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actually froze. Then, as a *diagnostic only*, raise `TdrDelay` (or set
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`TdrLevel=0`) under
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`HKLM\System\CurrentControlSet\Control\GraphicsDrivers` and see whether a
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previously-rebooting `make run` now only stutters/recovers — and read Event
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Viewer for **Display 4101** / **BugCheck 0x116** after any freeze. Revert the
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registry change afterward.
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