diff --git a/core/01_core.js b/core/01_core.js index 13aa17c7ed..d4a6508cb2 100644 --- a/core/01_core.js +++ b/core/01_core.js @@ -187,7 +187,16 @@ const cb = macrotaskCallbacks[i]; while (true) { const res = cb(); + + // If callback returned `undefined` then it has no work to do, we don't + // need to perform microtask checkpoint. + if (res === undefined) { + break; + } + ops.op_run_microtasks(); + // If callback returned `true` then it has no more work to do, stop + // calling it then. if (res === true) { break; } diff --git a/ext/web/02_timers.js b/ext/web/02_timers.js index 19ebfaa0e4..27e2e953db 100644 --- a/ext/web/02_timers.js +++ b/ext/web/02_timers.js @@ -54,8 +54,10 @@ const timerTasks = []; let timerNestingLevel = 0; function handleTimerMacrotask() { + // We have no work to do, tell the runtime that we don't + // need to perform microtask checkpoint. if (timerTasks.length === 0) { - return true; + return undefined; } const task = ArrayPrototypeShift(timerTasks); diff --git a/runtime/js/99_main.js b/runtime/js/99_main.js index 8fd9a6bd94..511368141c 100644 --- a/runtime/js/99_main.js +++ b/runtime/js/99_main.js @@ -351,6 +351,12 @@ function promiseRejectCallback(type, promise, reason) { } function promiseRejectMacrotaskCallback() { + // We have no work to do, tell the runtime that we don't + // need to perform microtask checkpoint. + if (pendingRejections.length === 0) { + return undefined; + } + while (pendingRejections.length > 0) { const promise = ArrayPrototypeShift(pendingRejections); const hasPendingException = ops.op_has_pending_promise_rejection(