QuickJS engine: inline step execution + WASM module caching - #3049
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… WASM module caching
🦋 Changeset detectedLatest commit: af8a0d6 The changes in this PR will be included in the next version bump. This PR includes changesets to release 16 packages
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🧪 E2E Test Results✅ All tests passed Summary
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This was referenced Jul 22, 2026
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Summary
PR 2 of the QuickJS VM roadmap: performance work for the
WORKFLOW_VM=quickjsengine.Live-VM inline step execution. The QuickJS entrypoint now keeps the suspended VM alive (
startQuickJSWorkflowreturns a session withcontinueWithEvents) and drives an inline continuation loop per invocation:hook.getConflict(),setAttributes(), racing sleeps — advance before any step body blocks the invocation.WORKFLOW_MAX_INLINE_STEPSsteps created by this invocation are executed inline, in parallel (executeStep+ in-process single-flight), with theReplayBudgetpaused during step bodies. Terminal events are fed back into the same live VM — no fresh-VM re-replay and no queue round-trip per step.wait_completedat the right log position while this one is busy. This is what keepsPromise.race([step, sleep])semantics.deliveryAttempt > 1triggers backstop step messages. (Ownership-lease stamping like the node engine'sownerMessageIdmodel is a noted follow-up; the interim model can rarely double-run a step body cross-instance, within the documented at-least-once step contract.)attr_set/getConflictimmediate-requeue round-trips — those now resolve in-process.Process-wide WASM module caching.
WebAssembly.compileof the QuickJS runtime (~600 KB) and its native extensions now happens once per process (shared promise), instead of on every invocation.The VM interrupt budget is now per-execution-burst (reset on each
continueWithEvents) instead of per-VM-lifetime, since sessions legitimately live for minutes across inline step bodies.Results (local dev, world-local, nextjs-turbopack)
hookWorkflowacross ~25 runs — under investigation, also being watched on the base branch)fibonacciWorkflow−10%,writableForwardedFromStepWorkflow−36%); the intended payoff is cloud worlds where each queue hop is a network round-trip. Suite wall-clock is dominated by fixed sleeps and unchanged (±2%).Notes
dispatchPendingOps) no longer queues steps at all — queueing is a caller decision (queueStepMessage), keeping drain semantics identical to the node engine'sdrainPendingQueueItems.