java memory analyzer

Recently, a project was designed to obtain information about the cpu usage and so on. At first, I thought it was necessary to use a dynamic link library, but later I found that I could do the following without calling jni, this saves a lot of time for reading new technologies... In Java, you can obtain information such as the total physical memory, the remaining physical

visible to thread 1, so the normal variable is not guaranteed to be visible .When you put the variable stop with the volatile modifier, the main thread modifies the stop variable to be immediately visible to thread 1 and terminates the program, which proves that the volatile variable is of a visibility nature . The following modified results.Atomic properties have been made clear (for arbitrary (including 64-bit long and double types) of a single volatile variable read/write has atomicity), rem

Java stack Memory heapJava divides memory into two kinds, one called stack memory, and the other is called Heap memory, which has different functions. Stack memory is used to store local variables and method calls.Stack

Java/io/file 788 1 java/io/file jmap Jmap-dump:format=b,file=dump.bin PID Jmap can obtain a specific memory match from a core file or process, including heap size, Perm size, and so on, which is only available in the Solaris and Linux JDK versions. Observe the physical memory footprint of a running JVM Prints out the

overflows typically occur after the old or perm segment garbage collection, and there is still no memory space to accommodate new Java objects.From the definition, it can be seen that the internal leakage is an inducement of memory overflow , not the only factor.Three, memory leakage of several scenarios:1. Long life

memory in the destructor, so a memory leak occurs only once.4. An implicit memory leak. The program keeps allocating memory while it is running, but it does not release memory until the end. Strictly speaking, there is no memory

memory leaksSummarize:We operate certain variables, the IDE provides us with a very good convenience, the JVM encapsulates a good automatic garbage collection mechanism for us, but we still that sentence, people are unreliable, this sentence makes us know ourselves repeatedly, the same, memory problems, we also need to delve into, Because this is the inevitable place for large-scale software optimization!

Java runtime memory Zone When running a Java program, the Java Virtual Machine divides the memory areas it manages into multiple different areas. Each region has its own purpose, Creation Time, and destruction time. Some exist with the startup of virtual machines, and some

Original link: http://www.cnblogs.com/laoyangHJ/archive/2011/08/17/gc-Stack.htmlDrill down into Java Virtual machines: stacks and heap in the JVMIn the JVM, memory is divided into two parts, stack (stack) and heap (heap), where we know the stack and heap from the perspective of the memory management principle of the JVM, and these principles recognize the problem

Java divides memory into two types: one is stack memory and the other is heap memory.Some of the basic types of variables and reference variables defined in the function are allocated in the stack memory of the function. When a variable is defined in a block of code, Java al

Various areas of Java Virtual machine memoryThe role of these areas, the service objects and the problems that may arise, respectively. (Image from Network)1. Program counterA program counter is a small piece of memory that can be seen as the line number indicator of the bytecode that is being executed by the current thread. The function of bytecode interpreter is to change the value of the program counter

cause a memory overflow in that area, which is generally the error message when a memory overflow occurs in this area:Outofmemoryerror:permgem Space2. Thread Stack Overflow (java.lang.StackOverflowError)Thread stacks a piece of memory structure that is unique to threads, so a thread stack problem must be an error that occurs when a thread is running. Generic thr

One, Java Virtual machine memory partition1. Program counterThread PrivateCan be seen as the line number indicator of the byte code executed by the current thread . The bytecode interpreter works by changing the value of this counter to select the next byte-code instruction to execute.A Java Virtual machine is implemented through multi-threaded rotation and alloc

Java divides the memory into two types:A kind of called stack memoryA heap of memory calledStack Memory : Some basic types of variables and object reference variables defined in the function are allocated in the stack memory of the function. When a variable is defined in a

In data structures, heaps and stacks can be said to be the two most basic data structures, and what are the similarities and differences between stack memory space and heap memory space in Java, and what is the relationship to the stack in the data structure?One, Java heap storage spaceHeap

There is a high wall between Java and C + + that is surrounded by dynamic memory allocations and garbage collection techniques, and people outside the walls want to go in, but the people inside the wall want to come out.Overview:Speaking of garbage collection (garbage Collection, hereinafter referred to as GC), most people regard this technology as the companion product of the

2.1 Run-Time data regionsThe Java Virtual machine divides the memory it manages into several different data regions during the execution of a Java program. These zones have their own purpose, as well as the creation and destruction of time, and some regions exist as the virtual machine process starts, and some regions depend on the user thread's start and end to

The previous time to learn the binary tree in the processing of the delete operation encountered a headache problem: the deletion of the node when it is clear that the node is still present on the tree, you must also execute Node.father.left = null, you can delete the node nodes, Looking for a reason to find out or because the Java memory management understanding is not deep enough.The code is as follows:@T

Java divides memory into two types: one is stack memory and the other is heap memory. Some of the basic types of variables and object reference variables defined in a function are allocated in the stack memory of the function. When a variable is defined in a block of code,

Program counter: A line number indicator that can be viewed as the byte code executed by the current thread, and in the conceptual model of the virtual machine, the bytecode interpreter works by changing the value of the counter to select the next byte code instruction to execute. Because JVM multithreading is implemented through the way that threads switch and allocate processor execution time, at any one time, a processor executes only the instructions in one thread. In order for the thread to