V8 implements a generational garbage collector - meaning it has a memory segment called new space for the young generation, and has an old space for the old generation. New objects are allocated in the new space, and if they survive two garbage collections in the new space, they are moved to the old space.
The problem with the two spaces is that moving objects between them is expensive: the objects need to be copied over, and the pointers must be updated. Moving out from the young generation is called evacuation, while adding it to the old generation is called compaction.
Since there are no dependencies between young generation evacuation and old generation compaction, the garbage collector can perform these in parallel, resulting in a reduction of compaction time of 75% from ~7ms to under 2ms on average.
#2: Track Pointers Improvement
When an object is moved on the heap, the garbage collector has to update all the pointers - but first, it has to find all the pointers to the old location. For this V8 uses a data structure called remembered set to keep track of interesting pointers in the heap. A pointer is classified interesting if the next garbage collector run may move it:
- moving objects from the young generation to the old generation,
- pointers to objects in fragmented pages, as objects may be moved to other pages during compaction
In older versions of V8, remembered sets are implemented using store buffers. This contains addresses of all incoming pointers. The problem is that it may result in duplicated entries, because a store buffer may end up including a pointer multiple times and two store buffers may have the same pointer. This would make parallelization of the pointer update really complex.
Instead of dealing with the extra complexity, Orinoco removes it by reorganizing the remembered set. Instead of the previous approach, now each page stores the offsets of the interesting pointers originating from the given page. With this technique the parallel updates of the pointers become feasible.
It has a huge performance impact - it can reduce the maximum pause time of compacting garbage collection by 40%.
#3: Black Allocation
The Black Allocation introduced by Orinoco is involved in the marking phase of the garbage collector. With this, once an object is allocated in the old generation, they are marked black instantly, meaning that they are "live" objects. The goal of this allocation is that objects allocated in the old space are likely to live longer, so they should survive the next garbage collector. Objects colored black are not visited by the garbage collector - they are put on black pages of the old space.
It speeds up the garbage collection due the faster-marking progress as well as less garbage collection work in general.why were hiv and t helper cells mixed in the presence and absence of cytotoxic t cells? How old do you have to get a driver's license? How to use apple pay on watch? How to euthanize a dog with over the counter drugs? What kind of meat is steak tips? What does 15 years to life mean? What is rickets? What are bait dogs? What does mf mean? How to reduce period cramps? How to become a substitute teacher? Why people use memory tricks? How to use rolling paper tips? What is the meaning of semi precious stones? Tips how to warm your tent? What do angel numbers 444 mean? How to get over covid faster? What does convoluted mean? What is a spac? What age does amc hire? How to stop a month long period? What are commercial tricks? Tips how to manage analyze and interpret survey data? What does it mean when your cat purrs? How to make whiskey sour? Elden ring how to level up? What is the meaning of marianne? What is the meaning of include? What is the meaning of support and resistance in trading? What are plasmids? Which trekking pole tips to use? What does fabrication mean? What does hai mean? What time does kirby and the forgotten land release? What does it mean when cats purr? What is character sketch meaning? How to attach pickets tips? What does fwb mean in text? What does bussit mean? What animals are herbivores? What does a hickey look like? What is the meaning of chili? What does the lord require of you? How to get rid of a pinched nerve? What is the meaning of pompeii? What do lmao mean? A steeple is when you lightly tap the tips of your fingers together mason? When a girl licks her lips meaning? How to get bigger penis? How to teach your guinea pig tricks? What do te amo mean in english? Instacart tips how much? how to set title key for wii u helper 3ds How to delete gmail account? Babe meaning when a guy calls you? What does overruled mean? How to edit videos? Why cant certain emplyees accept tips? False face must hide what the false heart doth know meaning? What tips can i use with edsyn loner? A heavy glass ball that you do hand tricks with is called what? What does 333 angel number mean? What are the two primary types of waves generated by earthquakes? How to insert text box in google docs? How to decline an interview? What tricks did faustus pull? What is the meaning of billow? How to get bigger calves? What time does knott's berry farm close? Tricks to use when to return a leased car? how to block lanschool web helper What do the 25 points of nazism meaning? What is the meaning of exemplary? What is donald trump doing now? How to lose weight while pregnant? What is the meaning of plaster? What does dpo mean? What is the meaning of deteriorating? Why do i get chills and my finger tips go numb? What does interloper mean? What does the numbers 888 mean? What does dep la meaning in raya? What does /p mean? How to make a music video tips? How to make turkey stock? how to install plexbmc helper What does ct mean in valorant? What is the meaning of obgyn? What is the meaning of danke? How to transfer contacts from phone to phone? What does neutrophils mean in a blood test? What does inri mean above the crucifix? How to qualify for fha loan? What is the meaning of disagreement? Tips for how to take the ancestry dna test? How to write electron configuration? How to get tips and dip off nails? What is the meaning of blue origin? How to season rice?