// Make enterWeakMarkingMode expensive so it gets forced into a single slice. // We need full control here. gcparam("concurrentMarkingEnabled", 0); gczeal(0); gc(); assertEq(gcstate(), "NotActive"); function checkFinishMarkingDuringSweeping(expected) { if (hasFunction["currentgc"]) { assertEq(currentgc().finishMarkingDuringSweeping, expected); } } var keys = []; var maps = Array(1000).fill().map(() => new WeakMap); for (const map of maps) { for (let i = 0; i < 100; i++) { // The key will die the next major collection , but will need to be put // into the ephemeron table first. let key = {}; keys.push(key); map.set(key, {}); } } minorgc(); keys = undefined; // Slowly work forward until we reach Mark. startgc(10); while (["Prepare", "MarkRoots"].includes(gcstate())) { gcslice(10); } assertEq(gcstate(), "Mark"); // Then continue until we reach Sweep. // // The last mark slice will yield before leaving marking, in order to give the // first sweep slice a full budget. // // The first Sweep slice will hit the long enterWeakMarkingMode and yield as // soon as the budget runs out, and set up the next Sweep slice to finish. while (gcstate() === "Mark") { gcslice(10000); } assertEq(gcstate(), "Sweep"); checkFinishMarkingDuringSweeping(true); // This slice will finish the marking, but will go way over budget and so will // yield as soon as the marking is done. This will still be during Sweep (in the // middle of sweepWeakCaches). // // Use more than gcslice(1) because it is possible to get a few things added to // the mark stack from read barriers. gcslice(100); assertEq(gcstate(), "Sweep"); checkFinishMarkingDuringSweeping(false); // There's still a lot of sweeping left to do, because all of the dead stuff // needs to be finalized. finishgc(); // Do another GC without a slow enterWMM, to confirm that the extra slice is not // requested. (The previous GC will have thrown out all of the WeakMaps' // entries, so this will just be doing one step for each of the 1000 WeakMaps // instead of 1000 * (1 + 100) for the WeakMaps plus their keys.) startgc(10); while (["Prepare", "MarkRoots"].includes(gcstate())) { gcslice(10); } assertEq(gcstate(), "Mark"); while (gcstate() === "Mark") { gcslice(100); } assertEq(gcstate(), "Sweep"); checkFinishMarkingDuringSweeping(false); gcslice(1); assertEq(gcstate(), "Sweep"); checkFinishMarkingDuringSweeping(false);