Very detailed GC study notes

I.GC characteristics and selection of various GC

1. Characteristics of garbage collector

2, the choice of garbage collector

2.1 Continuous VS. Parallel

2.2 concurrency VS. Stop-the-world

2.3 compression VS. do not compress VS. Copy

Second,GC performance Indicators

Third, the generation of recycling

Iv. GC learning on the HotSpot JVM ofJ2SE 5.0 - generational,GC Type, quick assign

V. GC learning on the HotSpot JVM ofJ2SE 5.0 -SERIALGC

Vi. GC learning on the HotSpot JVM ofJ2SE 5.0 -PARALLELGC

Vii. GC learning on the HotSpot JVM ofJ2SE 5.0 -PARALLELCOMPACTINGGC

Viii. GC learning on the HotSpot JVM ofJ2SE 5.0 -CMS GC

Nine, start parameter learning example

1. GC features and selection of various GC

1.1 Characteristics of the garbage collector

The recycled object must be recycled, and objects that should not be recycled must not be recycled.

Be sure to be effective, and be quick! Pause the app's run as little as possible

Need to balance the three elements of time, space, and recovery frequency

Memory fragmentation issues (a way to resolve memory fragmentation, which is compression)

Scalability and scalability (memory allocation and recycling should not be a bottleneck in multi-core multithreaded applications)

Selection of the garbage collector

1.2 continuous VS. Parallel

Continuous garbage collector, even in multi-core applications, when recycling, there is only one core to be exploited.

However, parallel GC uses multicore,GC Tasks are separated into multiple subtasks, and these subtasks are executed in parallel on each CPU .

the benefit of parallel GC is that it reduces GC time, but the disadvantage is that it increases complexity and there is the possibility of generating memory fragmentation.

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Very detailed GC study notes