JVM 选择合适的GC算法

 

Selecting a Collector

Unless your application has rather strict pause time requirements, first run your application and allow the VM to select a collector. If necessary, adjust the heap size to improve performance. If the performance still does not meet your goals, then use the following guidelines as a starting point for selecting a collector.

1. If the application has a small data set (up to approximately 100MB), then
   • select the serial collector with -XX:+UseSerialGC.
2. If the application will be run on a single processor and there are no pause time requirements, then
   • let the VM select the collector, or
   • select the serial collector with -XX:+UseSerialGC.
3. If (a) peak application performance is the first priority and (b) there are no pause time requirements or pauses of one second or longer are acceptable, then
   • let the VM select the collector, or
   • select the parallel collector with -XX:+UseParallelGC and (optionally) enable parallel compaction with -XX:+UseParallelOldGC.
4. If response time is more important than overall throughput and garbage collection pauses must be kept shorter than approximately one second, then
   • select the concurrent collector with -XX:+UseConcMarkSweepGC. If only one or two processors are available, consider using incremental mode, described below.

These guidelines provide only a starting point for selecting a collector because performance is dependent on the size of the heap, the amount of live data maintained by the application and the number and speed of available processors. Pause times are particularly sensitive to these factors, so the threshold of one second mentioned above is only approximate: the parallel collector will experience pause times longer than one second on many data size and hardware combinations; conversely, the concurrent collector may not be able to keep pauses shorter than one second on some combinations.

 

If the recommended collector does not achieve the desired performance, first attempt to adjust the heap and generation sizes to meet the desired goals. If still unsuccessful, then try a different collector: use the concurrent collector to reduce pause times and use the parallel collector to increase overall throughput on multiprocessor hardware.

 

Refrences：

Java SE 6 HotSpot[tm] Virtual Machine Garbage Collection Tuning