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value is usually related to the execution of the application. Space occupied : a measure of space occupancy, such as the size of a heap. swiftness : When an object becomes a garbage object and it occupies space at a time interval that is available. Interactive applications require a lower pause time, while the total execution time is more than the non-interactive application requirements. Real-time applications have a higher demand for garbage collection pauses and time to garbage

continuous (not physically required), when implemented, can be fixed-size, or extensible, the current mainstream of virtual machines are extensible. If there is still not enough memory allocation and no expansion after the garbage collection is performed, the OutOfMemoryError:Java Heap Space exception will be thrown.There is much more to the heap area, which is described in detail in the next section, "Java memory allocation mechanism ".5, Method area: In the Java Virtual Machine specification,

Garbage collection-generationThe proxy is a mechanism adopted by the CLR garbage collector. its only purpose is to improve the application.ProgramPerformance, the use of the garbage collector to do the following:1: The newer the object, the shorter the lifecycleIt is similar to the stack principle. The local variables defined first after the first time are used to stay in the stack for a relatively long time.2: The older the object, the longer the lifecycle, Which will be explained later.3: recl

selection details refer to the JVM tuning documentation.Slightly explained, the parallel algorithm is a multi-threaded garbage collection, the recovery period will suspend the execution of the program, while the concurrency algorithm, but also multi-threaded recycling, but does not stop the application execution. therefore, the concurrency algorithm is suitable for some programs with high interactivity. After observation, concurrency algorithms reduce the size of younger

Heap Size SettingsThe maximum heap size in the JVM has three limitations: the data Model (32-BT or 64-bit) of the associated operating system, the system's available virtual memory limits, and the available physical memory limits for the system. Under the 32-bit system, the 1.5g~2g;64 is generally limited to memory unrestricted for the operating system. I test under Windows Server 2003 System, 3.5G physical memory, JDK5.0, Max can be set to 1478m.Typical settings: JAVANBSP; -xmx3550m-x

parallel algorithm is selected for the younger generation, and the selection details refer to the JVM tuning documentation.Slightly explained, the parallel algorithm is a multi-threaded garbage collection, the recovery period will suspend the execution of the program, while the concurrency algorithm, but also multi-threaded recycling, but does not stop the application execution. Therefore, the concurrency algorithm is suitable for some programs with high interactivity. After observation, concur

continuous (not physically required), when implemented, can be fixed-size, or extensible, the current mainstream of virtual machines are extensible. If there is still not enough memory allocation and no expansion after the garbage collection is performed, the Outofmemoryerror:java heap space exception will be thrown.There is much more to the heap area, which is described in detail in the next section, "Java memory allocation mechanism ".5, Method area: In the Java Virtual Machine specification,

cannot be recycled.Once such an object is found in the markup process, it is moved from the unreachable list to the root list, and when the tag is complete, the unreachable list remainsAll objects are literally garbage objects, and the next garbage collection is only limited to the unreachable list.Generational recyclingThe idea of generational recycling: dividing all memory blocks in a system into different collections based on their survival time, each of which is called a "generation"The fre

unwanted), can be fixed size or extensible when implemented, and the current mainstream virtual machines are extensible. 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 exception. There is much more to the heap area, which is described in detail in the next section, "Java Memory allocation mechanism." 5, methods area: In the Java Virtual Machine specification, the method area is treated

Ext.: http://unixboy.javaeye.com/blog/174173 Heap Size SettingsThe maximum heap size in the JVM has three limitations: the data Model (32-BT or 64-bit) of the associated operating system, the system's available virtual memory limits, and the available physical memory limits for the system. Under the 32-bit system, the 1.5g~2g;64 is generally limited to memory unrestricted for the operating system. I test under Windows Server 2003 System, 3.5G physical memory, JDK5.0, Max can be set to 1478m.

have a full view of the low-lying areas. Imagine standing on the top of the hill, overlooking the whole town, people on the road, houses are wrong, isn't it open-minded, quite a little hero's pride? Broadcast fairy town is located at the junction of the Central Plains and the saiwai. Its architectural style is self-contained. In the figure, this is the only che Ma Yi in the town, where the people who want to seek fairy from Kunlun are staying in the room. In addition, when it comes to the scene

memory. In this way, idle memory is continuously released, it also solves the memory fragmentation problem. This process can also be used to compress pointers. The garbage collector generally divides the objects in the managed heap into three generations, which can be called by GC. maxgeneration learns that objects are divided into generations based on the length of time they exist. The shortest score is

survive as a collection, which is older. Now we call them 1st generations. (For example, figure 3) If new objects are added to the heap, the new ones will be placed in the 0th generation. If the 0th generation is full, GC starts to run. This time, the first generation of surviving objects willCompress to 2nd generations (such as Figure 4 ). All 0th-generation objects are compressed into 1st-generation obj

Memory Leaks and workarounds1. Some phenomena before the system crash:EachThe garbage collection time is getting longer, from the previous 10ms extended to about 50ms, FULLGC time also has the previous 0.5s extended to 4, 5sFULLGC more and more times, the most frequent lapse of less than 1 minutes to do a FULLGCOlder generations of memory are getting bigger and older generations have no memory released afte

continuous (not physically required), when implemented, can be fixed-size, or extensible, the current mainstream of virtual machines are extensible. If there is still not enough memory allocation and no expansion after the garbage collection is performed, the Outofmemoryerror:java heap space exception will be thrown.There is much more to the heap area, which is described in detail in the next section, "Java memory allocation mechanism ".5, Method area: In the Java Virtual Machine specification,

no expansion after the garbage collection is performed, the Outofmemoryerror:java heap space exception will be thrown.There is much more to the heap area, which is described in detail in the next section, "Java memory allocation mechanism ".5, Method area: In the Java Virtual Machine specification, the method area is treated as a logical part of the heap, but in fact, the method area is not a heap (non-heap); In addition, in many people's blogs, the Java GC's generational collection mechanism i

method area is treated as a logical part of the heap, but in fact, the method area is not a heap (non-heap); In addition, in many people's blogs, the Java GC's generational collection mechanism is divided into 3 generations: The green age, the old age, the permanent generation, these authors defined the method area as "permanent generation", because, for the previous implementation of the Hotspot Java Virtual machine, the idea of the collection of

no expansion after the garbage collection is performed, the Outofmemoryerror:java heap space exception will be thrown.There is much more to the heap area, which is described in detail in the next section, "Java memory allocation mechanism ".5, Method area: In the Java Virtual Machine specification, the method area is treated as a logical part of the heap, but in fact, the method area is not a heap (non-heap); In addition, in many people's blogs, the Java GC's generational collection mechanism i

The CLR garbage collector divides objects according to the size of the space they occupy. Large objects and small objects are handled in a very different way. For example, memory defragmentation-the cost of moving large objects in memory is expensive, let's look at how the garbage collector handles large objects, and what the potential impact of large objects has on program performance. Large object heap and garbage collection In. Net 1.0 and 2.0, if an object is larger than 85000byte, it is c

often used together (Program Locality Principle), it is very important to provide a continuous blank memory space for the program. 2. Generation) Aging means to divide objects in heap into generations based on the length of time they exist,The shortest score is in The 0th generation, the longest score is in the 2nd generation, and the objects in the 2nd generation are usually relatively large.. The generation level is related to the Framework ver