how to monitor java memory usage

Process of memory recycling Java garbage collection is divided into three regions in the new generation, the old age, the permanent generationWhen an object is instantiated go to the Garden of Eden there is not enough space:If there is no garbage collection, the object is stored directly in Eden;If the Eden memory is full, a minor GC will be performed;Then ju

Jinfo: You can output and modify the opts of the Java process at runtime.JPS: Similar to PS on UNIX, used to show the local Java process, you can view the local running a few Java programs, and display their process number.Jstat: A very strong monitoring VM memory tool. can be used to monitor the size of various heap a

Even more, the GC cannot be recycled and the system crashes. GC is a program, not intelligent. It only recycles the garbage he thinks, rather than the garbage you think.GC garbage collection:Grabage Collection believes that anyone who has learned JAVA knows what this means. But how does it work?First, when managing the memory, the JVM always divides the variable management into new and old objects. The new

. The establishment of Java Virtual Machine needs to be implemented for different software and hardware platforms, considering the model of the processor and the type of operating system. This allows Java virtual machines to be implemented on UNIX, Linux, Windows, and some real-time operating systems on embedded processing chips such as SPARC architecture, X86 Architecture, MIPS, and PPC. 2. Unwanted

operations. Because the compiler often cannot determine exactly after a volatile write, whether to insert a storeload barrier (for example, a volatile write method immediately return). To ensure the correct implementation of volatile memory semantics, JMM has adopted a conservative strategy here: Insert a storeload barrier behind each volatile write or before each volatile read. From the perspective of overall execution efficiency, JMM has chosen to

Jinfo: You can output and modify the opts of the Java process at runtime.JPS: Similar to PS on UNIX, used to show the local Java process, you can view the local running a few Java programs, and display their process number.Jstat: A very strong monitoring VM memory tool. can be used to monitor the size of various heap a

export the memory footprint of the current Java process to facilitate analysis using specialized memory analysis tools such as: MAT. This command is helpful for analyzing whether there is a memory leak. How to use to view another article in this blog: using Eclipse Memory A

(releases) the garbage collector at an uncertain time ). This is also the reason why Java accounts for memory usage. In fact, the variables in the stack point to the variables in the heap memory, which is the pointer in Java.!Constant pool) A constant pool refers to som

process, corresponding to a stack frame in the virtual machine stack from the path of the stack from the process.Local method Stack:The local methods Stack (Native method Stacks) is very similar to the virtual machine stack, except that the virtual machine stack executes Java methods (that is, bytecode) services for the virtual machine, while the local method stack serves the Native method used by the virtual machine. The language,

leak, and it is possible that the application does use too much memory; this time, you can neither increase the number of JVM heaps, nor change your program to make him reduce memory usage. However, in most cases, a outofmemoryerror is a memory leak flag. One solution is to continue to listen to GC activity, to see wh

---restore content starts---Bibliography: In-depth understanding of Java Virtual Machine Zhou ZhimingThe Java Virtual machine Specification SE 7 release specifies that the memory managed by the Java Virtual machine will include the following runtime data regions.program Counter Register is a small amount of

application and calls hooks Based on win APIs. 12. sapmemory analyzer-is an open-source Java memory analysis software that can be used to help find memory leaks in Java programs. It is easy to find large memory blocks and verify who is occupying it all the time, it is base

every 10 to 20 seconds for a GUI program to be completed within half a second each time. Note: 1. Increasing the heap size reduces the GC frequency, but increases the GC time. When GC is run, all user threads are paused, that is, Java applications do not work during GC.2. The heap size does not determine the memory usage of the process. The

Original Address http://www.codeinstructions.com/2008/12/java-objects-memory-structure.htmlUpdate (December 18th): I ' ve posted here a experimental library that implements Sizeof for Java.One thing about Java-have always bothered me, given my C + + roots, is the lack of a-a-to-figure out how much memory is used by an

, and the data for the local variable exists in the stack memory. Local variables in the stack memory disappear as the method disappears.Member variables are stored in objects in the heap and are collected by the garbage collector.(ii) Stacks in Java memory allocationSome basic types of variable data and object referen

to the first address of the array or object in the heap memory, the variable in the stack becomes the referenced variable of the array or object. The referenced variable is equivalent to an array or an object name. Later, you can use the referenced variable in the stack in the program to access the array or object in the heap. The referenced variable is equivalent to an array or an object name. The referenced variable is a common variable. It is assi

outside the code block where the new statement is used to generate arrays or objects, the memory occupied by arrays and objects is not released, arrays and objects become junk only when no referenced variable points to it. They cannot be used, but still occupy the memory space, the garbage collector collects (releases) the garbage collector at an uncertain time ). This is also the reason why

process that uses it exits.In Linux, each file has 2 counters, I_count and I_nlink. I_count indicates the number of files being invoked. I_nlink represents the number of hard links. The jmap Command jmap command can be used to output all in-memory objects, and can even dump the heap in the VM into text as binary. You can output details of all objects in the memory of a specified

, under Windows is Jconsole.exe, under UNIX and Linux is jconsole.sh,jconsole can monitor the local application, also can monitor the remote application. To monitor the local app, execute Jconsole pid,pid is the Java process ID that is running, and if you do not have the PID parameter, then after executing the jconsole command, you will see a dialog box pops up, listing the local Java process, you can choos

data for the local variable exists in the stack memory. Local variables in the stack memory disappear as the method disappears.The member variable is stored in the object in the heap and is collected by the garbage collectorhttp://www.iteye.com/topic/6345302. Stacks in Java memory allocationSome basic types of variabl