garbage collector run

Serial Old collector for JAVA Garbage Collector and serial for garbage collection The Serial Old collector is a type of Garbage Collector in Java virtual machines. It is an Old version

executed), the user program continues to run, and the garbage collector runs on the other CPU.The difference between 1.2.Minor GC and full GC New Generation GC (Minor GC): Refers to the garbage collection action occurring in the new generation, because most Java objects have a characteristic of being out of d

), weak references (Weak Reference), virtual references (Phantom Reference) These 4 kinds of references are under the Java.lang.ref package:　　Strong references (Final Reference)Refers to references that are common in program code, such as Object obj = new Object (), as long as a strong reference exists, and the garbage collector never reclaims the referenced object.strong references have the following three

limit the number of threads to be collected) -xx:parallelgcthreads number of threads open for multithreaded garbage collector memory Recycle Three, Parallel scavenge collector Cenozoic collectors, using the replication algorithm Multithreading Collector The collector's concerns are different from those of other colle

with the thread, and out of the thread, so that the memory allocation and recovery of these areas are deterministic, there is no need to too much consideration of the recycling problem, because the end of the method or the end of the thread, memory naturally with the recycling. The Java heap and method areas are different and different! (How not to say the catchy), this part of the memory allocation and recycling is dynamic, it is the garbage

to be stopped, and a CPU executes only one thread.Concurrency: The user thread executes concurrently with the GC thread (not necessarily in parallel, may be alternately executed), the user program continues to run, and the garbage collector runs on the other CPU. At the point of view of a CPU, it is generally run conc

algorithm, multithreading concurrency. In order to achieve the shortest garbage collection quite a pause time for the target collector. The collector's collection process is divided into 4 steps: 1, initial tag CMS initial mark: This step will stop the world, but it takes a very short time to mark the objects directly associated with GC root. 2, concurrent tagging CMS concurrent mark: Takes a long time, th

ParallelScavenge collector for JAVA Garbage Collector The Parallel Scavenge collector is a type of Garbage Collector in Java virtual machines. Similar to the ParNew collector, it is a n

Parallel Scavenge collectors are JAVA one of the garbage collectors in a virtual machine. similar to the Parnew collector, it is a new generation collector. A parallel multithreaded collector using the replication algorithm. 1 , featuresParallel ScavengeThe collector's focus is different from other collectors,Paralle

takes a part of the thread (orCPUresources) and cause the application to slow down, the total throughput is reduced. CMSthe number of recycle threads started by default is (CPUQuantity+3)/4, i.e. whenCPUin the4garbage collection threads are up to a maximum of25%of theCPUResources. But whenCPUInsufficient4a time (e.g.2one), thenCMSThe impact on the user program can become very large, ifCPUwhen the load is relatively large, it also divides half of the computing power to execute the

, this collector cannot completely surpass the Serial collector in two CPU environments implemented through hyper-Threading Technology. Of course, as the number of CPUs that can be used increases, it is very beneficial for the utilization of system resources during GC. The number of collection threads enabled by default is the same as the number of cpus. There are a lot of CPUs (for example, 32, the CPU is

). Parallel Scavenge Collector:The Parallel scavenge collector is also a new generation garbage collector, also using the replication algorithm, also a multi-threaded garbage collector, it focuses on the program to achieve a controllable throughput (Thoughput,cpu used to

machines use the "generational collection" (generational Collection) algorithm, which is divided into several blocks based on the lifetime of the object, generally dividing the Java heap into the new generation and the old age, so that the appropriate collection algorithm can be used according to the characteristics of each age. In the Cenozoic, every garbage collection found that a large number of objects died only a small amount of survival, only a