young garbage collection

generation, it uses different algorithms to recycle young generation.The CMS uses one or more background threads to periodically scan the old generation to reclaim unused objects, so it does not need to stop the application thread. However, because of the presence of a background thread, the CMS increases the load on the CPU and the background thread does not compress the heap.When there is insufficient CPU resources available or too much fragmentati

spaces are movedPermanent SPACE:JVM uses metadata, such as ClassLoader-loaded Class/method definitions (reflected data).Code Cache: Used to compile and store original codesPermanent space and code cache are not part of the Generation Collector recovery range.how to collect in generationsThe new object is initially assigned in Eden and fires minor garbage collection when Eden is full.Minor GC (also known as

The garbage collection mechanism is a dynamic storage allocation solution that automatically releases allocated memory blocks that are no longer needed by the program. PHP also implements dynamic memory management at the language layer. the dynamic management of memory saves developers from tedious memory management. the garbage

, it does not clean the recyclable object directly, but instead moves the surviving object to one end and then cleans up memory outside the end boundary.4) Generational collector generationalThe generational collection algorithm is the algorithm used by most of the JVM's garbage collectors today. Its core idea is to divide the memory into several different regions based on the life cycle of the object's sur

Click to enter _ more _java thousand ask1, how to judge the garbage objectThe first step in garbage collection is to first need an algorithm to mark what is garbage and then dispose of the garbage. The usual programming language will be judged using one of the following algo

Click to enter _ more _java thousand ask 1, how to judge the garbage object The first step in garbage collection is to need algorithms to mark which ones are garbage, and then to dispose of the garbage. The usual programming language is judged by one of the following algorit

1. Common algorithms:A. Reference counting method: Configure an shaping counter for each object, when there is a reference, counter +1, when the reference fails, counter-1. Counter 0 for garbage collectionProblem: A object reference b,b object reference A. Circular reference, cannot be purged, causes memory leakThe Java garbage collector does not use the algorithmB. Tag-purge algorithmThe tagging phase and

-sweep, but after the token is completed, it does not clean the recyclable object directly, but instead moves the surviving object to one end and then cleans up memory outside the end boundary. The exact process is as follows:4.Generational Collection (generational collection) algorithmThe generational collection algorithm is the algorithm used by most of the JVM

heaps);For the stable state of the program, may only produce very little garbage, this time "stop-copy" the comparison of waste time;　　Marking--Cleaning:Object discovery:The process is similar to "stop copying", which sets the tag for the surviving object during traversal;Processing:Objects that are not marked are garbage, recycled, not duplicated, and may cause memory discontinuities.　　Generational

object lifecycle analysis. Objects are divided into young, old, and persistent generations. Different algorithms (one of the above methods) are used to reclaim objects in different lifecycles. The current garbage collector (beginning with j2se1.2) uses this algorithm. By system thread Serial collection:Serial collection uses a single thread to process all

life cycle. Divide the objects into young, old, and persistent generations, using different algorithms (one of these methods) for different life cycle objects. The current garbage collector (starting with j2se1.2) uses this algorithm.divide by system threadSerial collection: Serial collection uses single-threaded proc

program cannot recycle its memory space and the system does not have any memory space to allocate when the program runs, the program will crash. Generally, the memory space that we can't recycle After allocating is called "Memory leakage (memory leaks )". The potential danger of the above program design is not allowed in a rigorous and secure language such as Java. However, the Java language neither limits the flexibility of programmers to write programs nor removes part of declared objects (o

Garbage collection is used to achieve automatic memory management, which is different from manual management ). Problems with manual memory management: 1) suspension pointer, dangling pointer2) repeated recovery, double free3) Memory leakage, Memory Leak HistoryJohn McCarthy invented the concept and technology of garbage col