JSThreadsAndGC: Difference between revisions

Jump to navigation Jump to search

JSThreadsAndGC (view source)

Revision as of 03:10, 23 April 2010

2,130 bytes added ,  23 April 2010
→‎Plans
No edit summary
Line 19: Line 19:
==Plans==
==Plans==


Add API for creating a global object and associating it with a compartment. Use it in Gecko everywhere we create a global. Add API JS_GetObjectCompartment.
These plans are limited to bugs that are part of the main central body of work to get us to per-tab GC, which we hope will dramatically reduce pause time.


Add assertions that there are no direct references across compartments, both at API boundaries and within the engine.
{| width="80%" cellspacing="1" cellpadding="6" border="0"
|-
! scope="col" | Name
! scope="col" | Size (weeks)
! scope="col" | Assigned to (guess)
|-
| Benchmark automation
| 0.5
| jorendorff/gwagner
|-
| Compartments and wrappers API
| 0.5
| jorendorff
|-
| Compartment assertions
| 1
| jorendorff
|-
| GCSubheaps
| ?
| gwagner
|-
| MT wrappers
| 3
| jorendorff
|-
| Lock-free allocation and slot access
| 1
| jorendorff
|-
| Compartmental GC
| ?
| gwagner
|}


Add API for creating objects that hold a single hard reference across compartments (use Proxy for this, I hope).
'''Benchmark automation''' — We need a way to turn a crank and get GC performance numbers: overall speed, length of longest pause, and total time spent in GC for several GC-intensive benchmarks. sayrer should get mail when we make these numbers move. This sort of data might as well be available via jsdbgapi.h in release builds. It won't be expensive to collect.


Factor GC-related code into a class, js::GCHeap. Then divide it into two parts: the top-level GCHeap, which can do whole-runtime GC, and Subheaps that can be GC'd individually.
'''Compartments and wrappers API''' — Add API for creating a global object and associating it with a compartment. Use it in Gecko everywhere we create a global. Add minimal API for a special kind of object that is allowed to hold a strong reference across compartments (a wrapper object). Use it in XPConnect for our security wrappers.
 
'''Compartment assertions''' — Add assertions that there are no direct references across compartments, both at API boundaries and within the engine. Fix what breaks. In particular, wrappers and the structured clone algorithm will need to copy strings and doubles instead of passing them freely from one compartment to another.
 
'''GCSubheaps''' — Factor GC-related code into a class, js::GCHeap ({{bug|556324}}). Carve out a second class, GCSubheap, so that a single GCHeap can have several GCSubheaps, each of which handles its own set of VM pages from which individual GC things may be allocated. Give each compartment its own GCSubheap. Allocate every object, double, and string from the GCSubheap for the compartment where it will live.
 
'''MT wrappers''' — Implement an automatically-spreading membrane of proxy objects that allow one thread to access objects from another compartment that is running in another thread. There is some risk here because it's unclear how this should work regarding objects on the scope chain (global objects, Call and Block objects). See {{bug|558866}} comments 1-4.
 
'''Lock-free allocation and slot access''' — Remove locking from allocation paths. Remove scope locking everywhere. ({{bug|558866}})
 
'''Compartmental GC''' — Support collecting garbage in one GCSubheap without walking the rest of the graph ({{bug|558861}}).


Make compartments the same thing as Subheaps.
Make compartments the same thing as Subheaps.
Jorend
638

edits

Retrieved from "https://wiki.mozilla.org/Special:MobileDiff/217960"

Navigation menu