Sun's Garbage First Collector Largely Eliminates Low Latency/High Throughput Tra

[CyanPrime]

Sun’s Garbage First garbage collector (hereafter referred to by its nickname G1) is the new low latency garbage collector planned to replace CMS in the Hotspot JVM. It is a server-style collector, targeted at multi-processor machines with large amounts of memory. There are two major differences between CMS and G1. The first is that G1 is a compacting collector. Compacting, a process by which live objects are moved over free memory space towards one end of the heap so that the other becomes one contiguous free area of memory, is important in long running applications because it is inevitable that the heap will fragment over time. G1 compacts sufficiently to completely avoid the use of fine-grain free lists for allocation, which considerably simplifies parts of the collector and mostly eliminates potential fragmentation issues. As well as compacting, G1 offers more predictable garbage collection pauses than can be obtained with the CMS collector and allows users to set their desired pause targets.

Sun's Garbage First Collector Largely Eliminates Low Latency/High Throughput...

[Riven]

On a sidenote:

it is really a lot better for a large heap, as the heap is split into ~1MB chunks, which are about as fast to collect as eden.

HOWEVER… there is considerable overhead: the overall performance is lower, yet more predictable.

[princec]

Predictable is almost always best, especially for the likes of us.

Cas

[Mr_Light]

ne levels need to be loaded as fast as possible no?

Hmm I wonder how much research has gone into replacing garbage collector (stratagies) on the fly.

[Riven]

@Mr_Light

Hmm I wonder how much research has gone into replacing garbage collector (stratagies) on the fly.

Shouldn’t be too hard… just copy everything from oldHeap to newHeap