how to monitor java memory usage

First, install the JprofilerDownload 5.1.2 from http://www.ej-technologies.com/and request a trial serial numberSecond, the main function of the introduction1. Memory ProfilerThe memory view portion of Jprofiler can provide a dynamic memory usage update view and a view that displays information about

1. Types of Java referencesMemory management is divided into: memory allocation and memory reclamation. are handled automatically by the JVM. The state of an object in memory: reachable, recoverable (call the Finalize method before recycling), unreachable JVM Recovery criteria: whether there are referenc

itself is not freed, and the groups and objects become garbage and can no longer be used when no reference variable points to it. , but still occupies memory and is released by the garbage collector at a later indeterminate time. This is also the main reason for the memory of Java comparison, in fact, the variables in the stack point to the heap

, 185 sleeping, 0 stopped, 0 zombieCpu (s): 0.0%us, 0.0%sy, 0.0%ni, 99.9%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%stmem:16294180k Total, 1601224k used, 14692956k free, 262596k buffersswap:8191992k Total, 0k used, 8191992k free, 646996k cached PID USER PR NI VIRT RES SHR S%cpu %MEMtime+COMMAND23386 Root 0 12.4g 299m 10m S 0.3 1.9 0:00.02 Java23387 Root 0 12.4g 299m 10m S 0.0 1.9 0:07.63 Java23388 Root 0 12.4g 299m 10m S 0.0 1.9 0:00.08 Java23389 Root 0 12.4g 299m 10m S 0.0 1.9 0:00.07 Java23390 Root 0 12.

The Java. Lang. runtime class provides the java. Lang. runtime class to view the current JVM memory usage. Each Java instance (Virtual Machine instance) has only one runtime instance. You can use runtime. getruntime () to obtain the runtime Instance Object of the current vir

Tags: ack c in load Java Stack Monitor Linux inter htop chargereproduced the top after the use of detailed parameters, the notes were not found, reproduced, as a reference for future use:Original address: http://blog.csdn.net/linghao00/article/details/8059244Linux top command view memory and multi-core CPU usage tell me about the multi-core CPU command mpstat-p A

Recently, I suffered from virtual memory and received reports saying that our products will be restarted from time to time, and the report said that "the memory used exceeds 5 GB ". Restarting is the mechanism of our product. We will monitor the memory, perform GC and restart the application beyond a certain limit, but it is too exaggerated to exceed 5 GB, the

semantics:1) Changes to variables are visible to all threadsUnderstand:　　Each use variable in a thread requires successive read->load->use operations, that is, each usage updates the variable value from the main memory so that the other thread's modifications are visible to the thread.Each time a thread assign a variable, it needs to perform several assign->store->write operations sequentially, that is, it

, in addition to defining a set of specifications, also provides a series of primitives, encapsulated the underlying implementation, for developers to use directly.This article is not intended to introduce all of the keywords to their usage, because there is a lot of information on the web for the use of each key word. Readers can learn by themselves. A key point to be introduced in this article is that, as we mentioned earlier, concurrent programming

also offers many ways to help us save memory usage as much as possible. This is also discussed later. Let us first analyze the use of these five types of data and the internal implementation method.StringCommon Commands : SET,GET,DECR,INCR, Mset, Mget and so on.Scenario : String is the most common type of data, and normal Key-value storage can be categorized as such.implementation : String in the Redis int

causes garbage collectionPause_time pause time, one representing the start of garbage collection time, the other represents the end of the recovery of the pause timeD/DALVIKVM (9050): Gc_concurrent freed 2049K, 65% free 3571k/9991k, external 4703k/5261k, paused 2ms+2msNote the "3571k/9991k" value in this message, which represents the heap size used by the program.2. Using DDMSDdms in Eclipse provides a GUI that looks at memory

about releasing the local reference, and the Java VM is released when the native method returns to the caller. However, sometimes it takes a JNI programmer to display a free local reference to avoid excessive memory usage. So when do I need to show the release, and look at the situation:1 in a single native method invocation, a large number of local references a

as if, in the object reference graph, from any object, if you want to access object Y, you must pass object x, then object x is in the dominate position of object Y.As you can see, the concept of dominating the tree is actually associated with the previous retained size. The retained size of an object is the sum of the shallow size starting from this object and all the tree child nodes that begin with it.Also, all root nodes must be the top node in the tree, not necessarily.Heap dump file (heap

How to view the JVM configuration and generational memory usage of a running spark process is a common monitoring tool for online running jobs:1, through the PS command query PIDPs-ef | grep 5661You can position the PID according to the special characters in the command2. Query the JVM parameter settings of the process using the Jinfo commandJinfo 105007Detailed JVM configuration information can be obtaine

causes garbage collectionPause_time pause time, one representing the start of garbage collection time, the other represents the end of the recovery of the pause timeD/DALVIKVM (9050): Gc_concurrent freed 2049K, 65% free 3571k/9991k, external 4703k/5261k, paused 2ms+2msNote the "3571k/9991k" value in this message, which represents the heap size used by the program.2. Using DDMSDdms in Eclipse provides a GUI that looks at memory

author as an example to share with you the Java memory overflow and database lock table detection and processing solutions encountered during the development process. 2. memory overflow AnalysisMemory overflow refers to the amount of memory that cannot be recycled or used in the application system. In the end, the

itself by the JVM, containing the required memory for the method area, internal processing of the JVM, or optimization (such as Jitcompiler,just-in-time Compiler, the immediately compiled code cache), Code for each class structure, such as running a constant pool, fields, and method data, and methods and construction methods.The JVM memory contains the following sections: Heap

Java virtual machines can be dynamically extended, However, a fixed-length virtual machine stack is also allowed in the Java virtual machine specification, which throws a OutOfMemoryError exception when the extension fails to request enough memory. (3) Local method stackThe local methods Stack (Native method Stacks) is very similar to the virtual machine stack,

first and second rows above, it gives the memory allocation at the JNI and Java layers. If you find that this value keeps increasing, memory leakage may occur in the program. 2) Total PSS Information This value is the actual memory occupied by your application. With this information, you can easily identify which pr

to current Percentage of physical memory used by the%mem-process Total CPU time used by the time+-process, in units 1/100 seconds command-Process Name (command name/command line) Multi-u multi-core CPU monitoring In the top basic view, press the keyboard number "1" to monitor the status of each logical CPU: In the view above, the server has 16 logical CPUs, which are actually 4 physical CPUs. If you do not press 1, the average of all CPUs is disp