how to monitor java memory usage

First, let's take a look at the code for a program's memory overflow:1 Importjava.util.ArrayList;2 Importjava.util.List;3 Public classTestmemoryleak {4 Public Static voidMain (string[] args)throwsinterruptedexception {5listint[]> list =Newarraylistint[]>();6Runtime Run =runtime.getruntime ();7 intI=1;8 while(true){9 int[] arr =New int[1024 * 8];Ten List.add (arr); One if(i++% 1000 = = 0 ){ ASystem.out.pri

protection. Take an example to see:Private int i = 0; Public void SetI (int i) { this. i = i;} Public int Geti () { return i;}A very common set of getter/setter, assuming that a line enters upgradeable calls SETI (1), and the B thread calls the same object's Geti (), what is the return value of the B thread?The rules of the first occurrence principle are analyzed in turn. Since two methods are called separately by two threads, the rules of Procedure order do not apply here, and becau

Java heap memory ?? The heap in Java is the largest memory space managed by JVM. It is mainly used to store various types of instance objects.?? In Java, the heap is divided into two different regions: Young and Old ). The Young generation is divided into three regions: Eden

creates an object, the GC begins to monitor the address, size, and usage of the object. In general, the GC uses a heap approach to record and manage all objects in the heap (see Resources 1). In this way, determine which objects are \ "accessible \" and which objects are \ "Unreachable \". GC is responsible for reclaiming these memory spaces when the GC determines that some objects are \ unreachable \. How

command, you will see a dialog box pops up, listing the local Java process and selecting one to monitor. If you want to monitor remotely, add something to the JVM parameters of the remote server, because Jconsole remote monitoring is based on JMX, and for jconsole detailed usage, see the article specifically Jconsle, and I'll give you a detailed description of jconsole in my blog. 3:JVIUSALVMAfter JDK6 u

Machine specification, there are two exceptions to this area: if the thread requests a stack depth greater than the virtual machine allows, the STACKOVERFLOWERROR exception will be thrown If the virtual machine stack can be dynamically extended (most of the current Java virtual machines can be dynamically extended, but the Java Virtual Machine specification also allows a fixed-length virtual machine stack)

When using eclipse3.2 + myeclipse5 in WINXP, the memory usage is always insufficient. Change the eclipse. ini file in the eclipse folder as follows:-Vmargs-Xms128m-Xmx512m-XX: permsize = 64 m-XX: permsize = 128 m Or: Create a batch file eclipse. bat in the eclipse directory, open it in a text editor, and write the following content:Eclipse.exe-vmargs-xms128m-xmx512m-XX: permsize = 128 M-XX: permsize = 256 m

, the allocation object uses the new keyword, releasing the object is to assign all references to the object null, so that the program can not access the object, we call the ' unreachable ' state, the GC is responsible for retrieving all the unreachable state of the memory space. For GC, when a programmer creates an object, the GC begins to monitor the size, address, and usage of the object. Generally, GC u

Summary Although the Java Virtual Machine (JVM) and its garbage collector (garbage COLLECTOR,GC) are responsible for managing most of the memory tasks, a memory leak may still occur in the Java software program. In fact, this is a common problem in large projects. The first step in avoiding a

Java implements thread support at the language level. It provides a series of encapsulated classes and interfaces such as Thread/runnable/threadgroup, allowing programmers to efficiently develop Java multi-threaded applications. In order to achieve synchronization, Java provides the Synchronize keyword as well as the object's Wait ()/notify () mechanism, but behi

the 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 vari

. Fourthe thread exclusive zoneLocal methods Stack (Native method Stacks)The local method stack 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, and the local method stack serves the native method used by the virtual machine.Because the virtual machine specification does not enforce the language,

-sweep algorithm,Java memory is not structured, A virtual machine maintains a list of memory usage, which is called a "free list". Virtual machines allocate space for objects very often, and if you assign objects to multiple threads at the same time, concurrency security control is involved. There are generally two sol

1. IntroductionOne of the biggest advantages of the Java platform is its automatic memory management, which allows Java developers to not write their own code to manage the memory, thereby leaving the complex memory management to focus on the development of business logic.Th

immediately compiled code cache), Code for each class structure, such as running a constant pool, fields, and method data, and methods and construction methods.When the JVM starts, it retains a fixed amount of memory to the heap memory, which is not necessarily used by the JVM, but it can be determined that this portion of the reserved memory is not used by othe

describe the basic functions and working principles of Optimizeit.Optimizeit Profiler version 4.11 supports Application,applet,servlet and Romote application four class applications and can support most types of JVMs, including the Sun JDK series, IBM's JDK series, and JBuilder's JVM. And, the software is written by Java, so it supports multiple operating systems. The Optimizeit series also includes the thread debugger and code coverage two tools, wh

I. memory overflow type1. java. lang. OutOfMemoryError: PermGen spaceJVM manages two types of memory, heap and non-heap. Heap is used by developers. It is created at JVM startup. Non-heap is reserved for JVM and used to store class information. Unlike the heap, GC does not release space during runtime. If the web app uses a large number of third-party jar files o

I. memory overflow type1. java. lang. OutOfMemoryError: PermGen space JVM manages two types of memory, heap and non-heap. Heap is used by developers. It is created at JVM startup. Non-heap is reserved for JVM and used to store class information. Unlike the heap, GC does not release space during runtime. If the web app uses a large number of third-party jar files

Eclipse memory overflow error: Java. Lang. outofmemoryerror: Java heap space. 1. view memory: Workspace /. metadata /. plugins/org. eclipse. core. runtime /. settings/org. eclipse. UI. prefs, add show_memory_monitor = true to it, and restart eclipse to view the memory

Java Theory and Practice: Use Weak references to block memory leaks-Linux general technology-Linux programming and kernel information. The following is a detailed description. Although Java™In theory, a program written in a language does not have a "memory leak", but sometimes objects are not garbage collected after th