Foundation: Zend gen-0 of compiler_minimal hangs after compiletofile_done (link gate never finishes)

[PurHur]

Category

Foundation: · bootstrap-selfhost-link · Zend gen-0 fallback hang

Problem

When committed prelinked/bootstrap-gen0 is lowering-fingerprint stale, ./script/bootstrap-selfhost-gate.sh link falls back to Zend AOT of test/selfhost/compiler_minimal/main.php. Under PHP_COMPILER_DOCKER_MEM=16g the emit succeeds (build/selfhost runs and prints compiler_minimal bundle OK) and progress reaches runtime_standalone_compiletofile_done, but php bin/compile.php never exits — it stays at ~100% CPU / ~4.7 GiB RSS for 15+ minutes after the artifact is stable. The link gate therefore never reaches the smoke loop or prints bootstrap-selfhost-link: OK.

Probed 2026-08-17 on master @81c0eecf41 (post-#31725).

Step	Result
Default 10g docker mem	Fail-fast #31714 (expected)
Remount 16g + Zend gen-0	Artifact written + runs OK; compile.php hung after compiletofile_done
Manual ./build/selfhost	compiler_minimal bundle OK (exit 0)

php-src reference

N/A (compiler pipeline / AOT teardown). Related history: #21925 (intermittent post-OK abort), #31714 (16g remount).

PHP implementation target

• bin/compile.php / lib/AOT/ / lib/JIT/ path after runtime_standalone_compiletofile_done — must exit 0 once -o artifact is linked
• Optionally script/bootstrap-resolve-compile-invoke.sh / link gate: treat stable executable + progress marker as success with a bounded wait (do not hang forever)
• No new runtime/*.c

Repro

docker info >/dev/null
# ensure gen-0 fingerprint is stale (normal tip drift)
PHP_COMPILER_DOCKER_MEM=16g PHP_COMPILER_DOCKER_MEM_SWAP=16g \
  ./script/docker-exec.sh -- bash -lc './script/bootstrap-selfhost-gate.sh link'
# observe: build/selfhost becomes runnable while php bin/compile.php continues at 100% CPU

Done when

• Zend gen-0 of compiler_minimal exits 0 shortly after writing a runnable -o binary
• ./script/bootstrap-selfhost-gate.sh link at 16g prints bootstrap-selfhost-link: OK (or native gen-0 path when fingerprint fresh)
• No fingerprint restamp; php-src-strict N/A (tooling/pipeline)

[PurHur]

claim: lane-B compile/link implementer — starting this run (bootstrap fallback; first red was #31714@10g, then Zend hang after successful emit)

[PurHur]

claim: lane-B implementer — continuing #31726 (post-compiletofile_done hang; investigating _exit before LLVM/PHP teardown)

[PurHur]

Merged #31741.

Fix: _exit(0) at end of Runtime::standalone() after successful selfhost compileToFile, before JIT Context destructor (LLVM teardown hang / #21925 abort).

Verified: SelfhostAotFastExitTest OK; tiny test/selfhost/ AOT exits with progress runtime_standalone_fast_exit.

[PurHur]

Merged #31742

Verification

• ./script/phpunit.sh --filter SelfhostAotFastExitTest — OK (6)
• Tiny selfhost AOT: rc=0 in ~14s after runtime_standalone_compiletofile_done
• PHP_COMPILER_DOCKER_MEM=16g PHP_COMPILER_DOCKER_MEM_SWAP=16g ./script/docker-exec.sh -- bash -lc './script/bootstrap-selfhost-gate.sh link' → bootstrap-selfhost-link: OK / compiler_minimal bundle OK (clean _exit; watchdog not needed)

Fix: warm libc _exit before LLVM; exit immediately after successful selfhost emit; Zend invoke watchdog as backup.