itouch generations

, such as Java Class, Method, etc., and the garbage collector to collect the Java object is not very related. And the heapspace is divided into young generation and old generation of the young generation of garbage collection called the Youth GC, old generation garbage collection called Full GC. Objects that survived after N (configurable) garbage collection in the young generation are copied into the old generation. As a result, older generations can

into two categories: Most objects soon cease to be used A part of it will not be immediately useless, but it will not last (too) long These observations form a weak-generation hypothesis (Weak generational hypothesis). Based on this assumption, the memory in the VM is divided into the younger generation (young Generation) and the older generation (old Generation). The old age is sometimes called the old Age Zone (tenured).Split into such two separate areas that can be cleaned,

Section I. Garbage collection Algorithms and complete collections (full GC) The garbage collector tracks all referenced objects, collates objects that are no longer referenced, reclaims the corresponding memory, and uses the "Mark and Purge" algorithm to recycle objects in two steps: Step 1.mark-sweep: From the application root, using the cross-reference relationship, traversing its dynamically allocated on the heap of all objects, indicating that the objects need to be recycled, mark the surv

% of the partition capacity, the G1 collector thinks it is a giant object. These mega objects, by default, are allocated directly to older generations, but if it is a short-lived mega-object, it can have a negative impact on the garbage collector. To solve this problem, G1 divides a humongous area, which is used to store giant objects. If an H-zone does not contain a giant object, then G1 will look for contiguous H-partitions to store. In order to fin

generation)Older generations store objects that live from young generations. In general, older generations are storing objects that are longer in their lifetimes.3. Perm (lasting generation)Used to store static files, Java classes, methods, etc. today. Persistent generations have no significant impact on garbage colle

areas is always empty.2. Tenured (older generation)Older generations store objects that live from young generations. In general, older generations are storing objects that are longer in their lifetimes.3. Perm (lasting generation)Used to store static files, Java classes, methods, etc. today. Persistent generations hav

. Divide the heap memory into young generations, mature generations, and permanent generations. The generational recycling mechanism uses different recycling strategies in different regions. The young generation was storing the new construction object, using copy and sweep. It is divided into 3 districts, Eden, from district, to district. Eden refers to the area

-monitoring object for synchronization Held by JVM -objects reserved for the special purpose of the JVM by the GC, but this is actually related to the implementation of the JVM. Some of the types that may be known are the system ClassLoader, the important exception classes that some JVMs know, some pre-allocated objects for handling exceptions, and some custom class loaders. However, the JVM does not provide additional information for these objects, so it is only left to the analyst to

algorithmUse a graph to summarize the layout of the heap memory according to the above contentModern commercial virtual machines are basically using generational collection algorithms for garbage collection. This algorithm is nothing special, but the combination of the above content, according to the different life cycle of the object to divide the memory into several pieces, and then according to the characteristics of each block using the most appropriate collection algorithm. A large number

(),2. When the counter of the GC module reaches the valve value.3. When the program exits Four. GC Module common function analysis Garbage Collector interface The GC module provides an interface for developers to set up garbage collection options. As mentioned above, one of the drawbacks of using reference counting to manage memory is circular references, and one of the main functions of the GC module is to solve the problem of circular references. Common functions: Gc.set_debug (Flags)Se

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about One-third to One-second of the heap size, but this is not a guideline, after all, it depends on the application logic. It is therefore better to investigate the rate of metamorphosis and the size of older generations of young generation to older generations, based on this (to ensure that older generations are too small to frequently promote GC-led memory o

continuous, so the distribution will be very fast; Likewise, the Eden area is recovering very quickly (because in most cases the Eden object survives a very short period of time, and the Eden area uses a replication recovery algorithm that is very efficient in the case of a small number of surviving objects, described later in detail). If you do not have enough memory allocations or extensions after the garbage collection has been performed, you will throw a Outofmemoryerror:java Heap space exc

collection. The little one needs more tests. Python divides all objects into three generations of 0,1,2. All new objects are 0-generation objects. When a generation of objects experiences garbage collection and survives, it is classified as a next-generation object. When garbage collection starts, all 0 generations of objects are scanned. If the 0 generation is garbage collected for a certain number of

generation size.Increasing the number of young generations will reduce the size of the older generation, which has a greater impact on system performance, Sun officially recommended configuration for the entire heap of 3/8 -xx:newsize Set young generation size (for 1.3/1.4) Set Young generation size -xx:maxnewsize Set the young generation maximum (for 1.3/1.4) Set maximum young generation size

About JVM memory generation, see this post, forward Link Address---thank you. The total partition in the virtual machine is three generations: young Generation, Old Generation, and persistent (Permanent Generation). The persistent generation primarily stores the class information of the Java class, which is not related to the Java objects collected by garbage collection. The division of the younger generation and the old generation is more significan

) Objects that survived after multiple GC in the Cenozoic are put into the old generation. Therefore, it can be considered that older generations are storing objects with longer life cycles. Older generations are much larger than the new generation of memory (roughly 2:1?). ), when the old generation of the time when the major GC, that is, full gc,full GC frequency is relatively low, older generat

area of memory. -server: This is the configuration that is applied to the server, and there is a special processing-xmx1024m inside the JVM: Set JVM maximum heap available memory is 1024mb-xms1024m: set JVM minimum internal storage to 1024m. This value can be set to the same as-xmx to avoid the JVM reallocating memory after each garbage collection completes. -xx:newsize: Set the young generation size-xx:maxnewsize: Set the maximum young generation size-xx:permsize: Set the permanent generation

marked for garbage, then when to be recycled, or when the GC began to work? Microsoft's official explanation is that the GC will only work when one of the following conditions is met: The system has lower physical memory; The memory used by the allocated objects on the managed heap is outside the acceptable range; Call the Gc.collect method manually, but almost all of the cases, we do not have to call, because the garbage collector will automatically call it, but in the above e

) { using (FileStream FileStream = new FileStream (@ "c \ Test.txt ", FileMode.Open)) { }}　　About algebra: Divided into 3 generations: No. 0 generation, 1th generation, 2nd generation. No. 0 Generation: This is the youngest generation, which contains short lifetime objects. An example of a short-lived object is a temporary variable. Garbage collection occurs most often in this generation. The newly allocated object forms the next