free java memory profiler

. -xx:permgen Sets the initialization size for the permanent generation of memory. -xx:maxpermgen Sets the maximum value for the permanent generation. -xx:survivorratio Provides the spatial proportions of the Eden and survivor areas. For example, if the size of the young generation is 10m and the VM switch is-xx:survivorratio=2, then 5m memory will

-xms64m-xmn32m-xss16mNote: If both the B and C settings are in the same development environment, the B setting takes effect and the C setting is invalid, such as:The development environment is set to:-xmx256m, and the class test is set to:-xmx128m-xms64m, the setting that is in effect when you run test is:-xmx256m-xms64m(3) When the JVM is started and used in a server environment (such as Tomcat) (the Java program is in effect for the current server e

1 shared memory corresponds to the significance of application developmentThe IPC (interprocess communication) mechanism is familiar to programmers familiar with the application development of UNIX systems, and the IPC basically includes shared memory, semaphore operation, Message Queuing, signal processing and other parts, which is an essential tool in the development of applications. The key to the IPC me

With regard to the allocation of Java memory, many problems are vague and cannot be fully understood. Look at the information, want to dig deeper, thoroughly clear the Java memory allocation context, only because of the level of limited, did not achieve the desired effect, only in this article to the study to record, f

to implement it. The local method stack and the Java stack are directly merged into the hotsopt virtual machine. 4. HeapIn the C language, this part of the heap is the only area of memory that a programmer can manage. Programmers can use the malloc function and the free function to apply and release space on the heap. So what's it like in

specific implementation mechanism of lock memory semantics.Take a look at the following sample code:Class Reentrantlockexample {int a = 0; Reentrantlock lock = new Reentrantlock ();p ublic void writer () { lock.lock (); Get lock try { a++; } finally { lock.unlock (); Release lock }}public void Reader () { lock.lock (); Get lock try { int i = A; ... } finally { lock.unlock (); Re

referenced by any handle, and becomes garbage, even though the handle P1 is still valid if it has not gone beyond its scope, but it has been assigned null and no longer points to any object. The P1 can then point to other person objects, because it has not yet exceeded its scope.(3) When an anonymous object is created, it becomes garbage when the anonymous object is exhausted. Cases:｛New Person (); //Because it is an anonymous object, no reference handle points to it, which is garbageNew person

In C + +, programmers have ownership of each object, but at the same time shoulder the responsibility of releasing the object's memory space, while Java has the help of a virtual machine, the programmer has ownership of the object and no longer need to free the object's memory space. Because the JVM automatically frees

Transferred from: http://www.iteye.com/topic/528230Java program memory is mainly divided into 2 parts, including stack segment (stack memory area), heapsegment (heap memory area).In analyzing the memory allocation of Java programs, let's start with a frequently used example.

1. Why memory leaks occurHow does Java detect internal leaks? We need some tools to detect and find memory leaks, otherwise it's easy to have a down-machine problem.The most convenient place to write Java programs is that we do not need to manage the allocation and release of memor