Garbage collectors in jdk 6
Garbage Collection JVM Optionsįollowing are the key JVM options that are related to Java garbage collection. Given all the above four types of Java garbage collectors, which one to use depends on the application scenario, hardware available and the throughput requirements. This option is introduced in Java 8 u 20. This optimizes the heap memory by removing duplicate String values to a single char array. Turn on the -XX:+UseStringDeduplication JVM argument while using G1 garbage collector. Turn on the –XX:+UseG1GC JVM argument to use the G1 garbage collector. G1 collector prioritizes the region based on most garbage first.
But CMS garbage collector compacts the memory on stop the world (STW) situations.
GARBAGE COLLECTORS IN JDK 6 FREE
G1 also does compacts the free heap space on the go just after reclaiming the memory. It separates the heap memory into regions and does collection within them in parallel. G1 garbage collector is used for large heap memory areas.
Turn on the XX:+USeParNewGC JVM argument to use the CMS garbage collector. If we can allocate more CPU for better performance then CMS garbage collector is the preferred choice over the parallel collector. In comparison with parallel garbage collector, CMS collector uses more CPU to ensure better application throughput.
GARBAGE COLLECTORS IN JDK 6 SERIAL
Similar to serial garbage collector this also freezes all the application threads while performing garbage collection. Unlike serial garbage collector, this uses multiple threads for garbage collection. It is the default garbage collector of the JVM. Parallel garbage collector is also called as throughput collector. Turn on the -XX:+UseSerialGC JVM argument to use the serial garbage collector. It is best suited for simple command-line programs. The way it works by freezing all the application threads while doing garbage collection may not be suitable for a server environment. It uses just a single thread for garbage collection. It is designed for the single-threaded environments. Serial garbage collector works by holding all the application threads. It is critical to understand each of these types of garbage collectors and use it rightly based on the application.
Each of these types differ largely and can provide completely different application performance. We can choose them by passing the choice as JVM argument. Most importantly, we the programmers can choose the type of garbage collector to be used by the JVM. Java has four types of garbage collectors,Įach of these four types has its own advantages and disadvantages. In the part 1 introduction to Java garbage collection, we saw about the JVM architecture, heap memory model and surrounding Java terminologies. In the previous part 2 we saw about how garbage collection works in Java, it is an interesting read and I recommend you to go through it. This is the third part in the garbage collection tutorial series. Garbage collection is an automatic process in Java which relieves the programmer of object memory allocation and de-allocation chores. In this tutorial we will go through the various type of Java garbage collectors available.