Comparison of garbage collection mechanisms in Java and. Net

Same point:

Have adopted the mechanism of generational.

Both support concurrent GC.

Have not adopted the reference counting method, but have adopted the tracking technology.

. NET, you can pass the code GC. Collect () enforces that the CLR is garbage collected (because garbage collection is asynchronous, the CLR has a dedicated thread responsible for garbage collection, so Even if you call Gc.collect, you do not call Finalize in real time, so to ensure that the destructor is actually called, you can use the statement gc.waitforpendingfinalizers () to ensure that the destructor is really running, refer to http://cnn237111.blog.51cto.com/2359144/1343004 )

garbage collection can also be enforced through System.GC () in Java. (In fact, it is only recommended that the JVM perform garbage collection, and the JVM does not necessarily do the recycling immediately.) )

Different points:

The CLR reserves a large space, called the large Object Heap (LOH), to be placed here when there are large objects (more than 85000 bytes) that need to be allocated space.

The difference between this place and the generational mechanism is that this place is recycled only when the full GC is in place, and the area is not compressed.

In Java, you can configure parameters so that large objects (greater than the set threshold) go directly to the old age (avoid doing a lot of copying on younger generations).

The memory that is reclaimed by the JVM is returned to the operating system only under certain conditions. (see:http://stackoverflow.com/questions/366658/java-6-excessive-memory-usage#367933)

. NET the recovered memory is returned directly to the operating system.

The JVM's garbage collection mechanism provides a number of configurable parameters.

The CLR's garbage collection mechanism is almost nothing to configure (the only configuration seems to be workstation mode (Workstation) and server mode (server)).

Both support concurrent GC. Java is a CMS collector that supports concurrent GC in the old age.

. NET concurrent GC is only available on the 2nd generation and only in workstation mode.

Java is divided into the young generation, the old age, the permanent generation.

. NET Sub-No. 0 generation, 1th generation, 2nd generation.

. NET used in the way of marking, compression.

Java is not limited to an algorithm because of its many collectors.

	Young generation	Old age	Way
Serial collector	Replication Algorithms		Single thread, Stop the world
serialold Collector		Marker Grooming algorithm	Single thread, Stop the world
Parnew Collector	Replication Algorithms	Marker Grooming algorithm	Multithreading, Stop the World
Parallel Scavenge collector	copy algorithm		Multithreading, Stop the World
CMS collector		Mark Clear	Single Thread
G1 Collector	Copy	Tag Grooming

Several articles on Java garbage collection

Http://www.cnblogs.com/shudonghe/p/3457990.html

http://blog.csdn.net/zhangerqing/article/details/8214365

. NET Garbage collection articles

https://msdn.microsoft.com/zh-cn/library/ee787088 (v=vs.110). aspx

Http://www.mincoder.com/article/4284.shtml

Comparison of garbage collection mechanisms in Java and. Net