Fix typespec-java emitter build hanging parallel pnpm build

[timotheeguerin]

Problem

A full-repo pnpm build intermittently hangs at the Java emitter build. The output stops right after:

@azure-tools/typespec-java:build: core-commit.json SHA ... using current checkout.

and never reaches Copy generator sources from core. Building packages/typespec-java on its own always works. Prior attempts (#4972, #4983, and non-interactive/fetch hardening) did not resolve it.

Root cause

turbo runs each task's process in its own background process group under the build's controlling terminal (the TUI). When a PowerShell cmdlet renders Write-Progress — which Copy-Item -Recurse in Copy-Sources.ps1 does — pwsh touches that terminal from a background process group and the OS stops the process with SIGTTIN/SIGTTOU (T state). It never resumes, so the build hangs forever.

This explains all the symptoms:

• Java-only: it is the only package that shells out to pwsh.
• Intermittent: Copy-Item only renders progress when the copy is slow enough (under parallel-build load).
• Invisible when piped / in isolation: with piped output (no TUI) or a standalone build, pwsh is not a background process group of a controlling terminal, so nothing stops it.
• Unaffected by -NonInteractive: progress renders regardless.

Reproduced directly: a pwsh running Write-Progress in a background process group under a controlling tty immediately enters T (stopped); with $ProgressPreference = 'SilentlyContinue' it never stops.

Fix

• Set $ProgressPreference = 'SilentlyContinue' in Copy-Sources.ps1, Build-Generator.ps1, and CoreCommit.ps1 so no cmdlet touches the controlling terminal. This is the actual fix.

Complementary hardening (removes secondary hang/network vectors):

• CoreCommit.ps1: only git fetch the pinned core commit when it is genuinely missing locally (git cat-file -e <sha>^{commit} first) — previously it hit the network on every emitter build / doc regen.
• CoreCommit.ps1: GIT_TERMINAL_PROMPT=0 and pwsh -NonInteractive (package.json) so a git credential/host prompt can never block the headless build.
• CoreCommit.ps1: extract pinned sources with [System.IO.Compression.ZipFile]::ExtractToDirectory instead of the pathologically slow Expand-Archive.

Verification

• Reproduced the T-state stop with Write-Progress under a controlling tty; confirmed $ProgressPreference='SilentlyContinue' prevents it.
• 8/8 runs of the real Copy-Sources.ps1 in a background process group under a controlling tty never stop.
• Full pnpm build completes 63/63; git -C core status stays clean.

[azure-sdk-automation]

All changed packages have been documented.

• ✅ @azure-tools/typespec-java

Show changes

@azure-tools/typespec-java - internal ✏️

Fix the Java emitter build intermittently hanging a full parallel pnpm build. The build scripts run under turbo, which puts each task in a background process group under the build's controlling terminal; when a PowerShell cmdlet (notably Copy-Item -Recurse) rendered Write-Progress, pwsh touched that terminal and the OS stopped it with SIGTTIN/SIGTTOU, hanging forever. The .ps1 build scripts now set $ProgressPreference = 'SilentlyContinue'. Also make the pinned-core/ fetch conditional (only when the commit is missing) and non-interactive (GIT_TERMINAL_PROMPT=0, pwsh -NonInteractive) to remove secondary hang/network vectors.

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/@azure-tools/typespec-java@5004

commit: cb93f66

[azure-sdk-automation]

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