.NET 4.5 includes new garbage collector enhancements for client and server apps

http://blogs.msdn.com/b/dotnet/archive/2012/07/20/the-net-framework-4-5-includes-new-garbage-collector-enhancements-for-client-and-server-apps.aspx

by noveltyaccount • 14 years ago

72 26 14 years ago

blogs.msdn.com

kevingadd4• 14 years ago

Being able to disable blocking gen 2 GCs for a period of time will be really useful for games and multimedia applications. You can disable the blocking GC during your update/render logic, then turn it back on while your main thread is blocked on vertical sync!

Being able to do this kind of scheduling aware GC would be a big boon for browser environments too. I've been pushing browser developers to do this and hopefully having working examples of it in other environments will help motivate them - see https://bugzilla.mozilla.org/show_bug.cgi?id=730113 for one example of how this might be done.

tinco6• 14 years ago

That is not a very good idea, a gc could easily take more time than your vsync, even if you didn't leak anything. It's smarter to profile your game and make sure it doesn't leak any memory, and perhaps use this feature to disable the GC altogether until play is interrupted.

kevingadd4• 14 years ago

How exactly do you propose 'not leaking memory' in runtime environments where everything creates garbage? In .NET you at least have structs, but other environments (like JS as I gave as an example) make it impossible or near-impossible to be garbage-free. Controlling the timing of your GCs is a win there, even if a long GC can make you miss a frame.

Half a GC happening during vsync instead of none of it is still a win because the hitch will be smaller.

alexro• 14 years ago

SustainedLowLatency is a killer for many types of scenarios. One is when you create many objects that you don't intent to GC throughout the life of the app, dictionaries for example.

Memory is cheap, being able to use it to increase performance of a managed app makes me really excited with how c# can be used in apps typically written in C++

thebluesky7• 14 years ago

> "The new background server GC in the .NET Framework 4.5 offloads much of the GC work associated with a full blocking collection to dedicated background GC threads that can run concurrently with user code, resulting in much shorter (less noticeable) pauses. One customer reported a 70% decrease in GC pause times. "

Concurrent garbage collection. Not that impressive in 2012. Java has had concurrent GC for at least a decade:

JDK 1.2.2 Java had a switch for that in the late 90's already: -Xconcgc Use concurrent garbage collector (1.2.2_07+)

JDK 1.4.2 http://java.sun.com/docs/hotspot/gc1.4.2/#4.3.%20When%20to%2...

also: http://research.sun.com/techrep/2000/abstract-88.html

The world has moved on:

http://www.oracle.com/technetwork/java/javase/tech/g1-intro-...

http://researcher.watson.ibm.com/researcher/view_project_sub...

kevingadd4• 14 years ago

The world has moved on from using threads? Citation, please. ;)

thebluesky7• 14 years ago

The world has moved on to more advanced concurrent GC implementations. Citations above.

tinco6• 14 years ago

Many other languages still don't have it, as I understand it implementing a concurrent garbage collector is always impressive, whether you did it 20 years ago or now.

I think this is indicative of their priorities. Java has had to fight the general opinion that it is a slow platform, so they built the best garbage collecting vm you could imagine. .Net has had to fight the opinion that it is just Java but on windows, so they built a multiple language oriented vm that enables language features so varied that even the standard java-like language C# rivals ruby and python in expression.

thebluesky7• 14 years ago

> built a multiple language oriented vm that enables language features so varied that even the standard java-like language C# rivals ruby and python in expression

Since the JVM happily runs Ruby, Groovy, Clojure, Python, Scala the point it moot. Aside from that C# does not rival Ruby in expressiveness.

kenjackson2• 14 years ago

You do realize that .NET has had concurrent garbage collection for a decade? It was workstation-only until recently (now?).

But background GC is different than concurrent GC (in the .NET world) in that background GC can collect ephemeral generations in the middle of a gen 2 background collection (this was a restriction of concurrent GC in the past). Background GC is in the current version of .NET, but it sounds like they've extended background GC to the server now.

While there are some great JVM GCs, I wouldn't walk away with the impression that the .NET folks are behind by any means.

thebluesky7• 14 years ago

Fair point. Thanks for pointing that out.

> "While there are some great JVM GCs, I wouldn't walk away with the impression that the .NET folks are behind by any means. "

Can the .NET GC provide deterministic real-time collection pauses? e.g.:

http://www.oracle.com/us/technologies/java/oracle-jrockit-re...

.NET 4.5 includes new garbage collector enhancements for client and server apps

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