jvisualvm | 易学教程

How to find memory leaks using visualvm

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问题 I suspect we have a major memory leak in our ActiveMQ connection bridge - we're seeing typical memory leak patterns (app loads fine, slows down if it runs for prolonged periods of time or is restarted over and over again over short periods of time). I looked up modern best practices for finding Java memory leaks and a lot of developers seem to be abandoning traditional tools like jhat/jmap in lieu of the new(er) jvisualvm . Upon launching this tool (and spending a few hours reading over its

Java 复习 —— 守护线程以及线程监测工具

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【推荐】2019 Java 开发者跳槽指南.pdf(吐血整理) >>> 1、守护线程 Java线程机制分为两种，用户线程（User Thread）和守护线程（Daemon Thread）。用户线程：运行在前台，执行具体的任务。例如：程序的主线程，连接网络的子线程。守护线程：运行在后台，为其他线程提供服务的。例如：垃圾回收器线程线程异同：一旦所有的用户线程都运行结束，守护线程会随JVM一起退出，其实这就是守护线程应该的生命周期，因为他是服务于其用户线程的线程，当用户线程一旦执行完毕，守护线程的职责就结束了，理该退出！但是用户线程是不会在主线程结束的时候而退出的。线程应用：用户线程一般执行在特定的任务上，守护线程一般使用在数据库连接池中的监测线程，JVM启动后监测线程等。 2、API Thread t1 = new Thread(sample); t1.setDaemon(true); t1.start(); 1）thread.setDaemon(true)必须在thread.start()之前设置，否则会跑出一个IllegalThreadStateException异常。换句话说，你不能把正在运行的常规线程设置为守护线程。 2）在Daemon线程中产生的新线程也是Daemon的。 3）注意读写操作或者计算逻辑是不能使用守护线程的。因为在Daemon

Why does heap space constantly increase when monitoring Tomcat with Java VisualVM?

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问题 I have a JRubyOnRails application running in Tomcat. After browsing to my application (localhost), logging in and then doing nothing, the Heap space seems to be growing continuously... Is that normal? If I press on Perform GC, it does go down again. I'm wondering what will happen if I just leave it until it reaches the maximum of my Computer RAM? And why is it increasing all the time while nothing happens? Is it due to the fact that I'm monitoring my application? 来源： https://stackoverflow.com

Monitor Tomcats internal threadpool without using JMX in a Spring Boot App

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问题 I have a simple Spring Boot web application set up for handling incoming http requests. Using the Java VisualVm I am able to see MBeans such as Tomcat's internal Threadpool. See the following screenshot: Screenshot of the Java VisualVM's MBean viewer I have successfully used JMX to monitor attributes such as "currentThreadCount" and "currentThreadsBusy". I set up Prometheus to access the monitored attributes as well. This works well. However, now I wanted to know if it is possible to access

jvisualvm: Stuck on “Loading Heap Dump…” screen

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问题 I am using jdk64 and my java version is "1.6.0_24". My tomcat is running with -Xmx7196m, and jvisualvm is running with -J-Xms2048m -J-Xmx3072m. I took a heap dump of my tomcat java process and size of my .hprof file is around 5.5 GB. When I try to open this heap dump, it just stuck on Loading Heap Dump... screen. I also looked at the heap consumption of VisualVM while it is trying to open the heap dump, but that goes around 500MB only. NOTE: I did look at jvisualvm: Stuck on “Loading Heap

Increasing the max size of jvisualVM OQL resultset

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问题 I have a memory dump file which has nearly 5000 instances of a particular object. These objects are to be written into a DB, and the way i am doing this is to write an OQL query in jvisualvm to generate a string that will serve as an SQL insert for example select "insert into trades (id, tradeNumber) values ("+ x.id+ ", " + x.tradeNumber +");" from com.test.application.TradeObject x; When i run this via OQL, i get a result set like this - <code> insert into trades (id, tradeNumber) values (1

JVisualVM Memory Sampling : Remote applications are not supported

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问题 I am trying to monitor remote tomcat process with JVisualVM in Red Hat Linux. CPU sampling works fine but Memory sampling tab is disabled. It says "Memory sampling: Not available. Remote applications are not supported" . Command line parameters of process: -Djavac.source=1.5 -Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.authenticate=false -Dcom.sun.management.jmxremote.ssl=false -Dcom.sun.management.jmxremote.port=11107 JVisualVm details: Version: 1.6.0_24 (Build 100930);

Is there any equivalent of JVisualVM on DotNET?

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问题 I would like to know if there is an equivalent of the excellent Java JVisualVM (included with JDK, the command is "jvisualvm") on the DotNet platform ? JVisualVM is a great tool that allows developers and admins to have really useful monitoring on any running Java application, here is some features that it has : Graphical view of the threads status Memory/CPU graphs Live heap dump CPU/Memory profiling Garbage Collector / JIT utilization graphs JMX calls Is there any equivalent on DotNet ?

jvisualvm - How to provide an icon and another name than the invoking class for my program?

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问题 I have an application where I want to be able to provide my own icon and descriptive text for jvisualvm. (I do not want to configure jvisualvm, just provide better metadata from my application) The best would be at runtime since we have distinct behaviour determined at runtime, which would be nice to have reflected in the label/icon. Makes it easier to 1) locate ourselves, but also 2) for endusers to locate in a support situation. I did search for this earlier, but did not locate this easily.

Why two instances of spring bean controllers are created in a Spring MVC application?

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问题 I have simple Spring MVC application with a jsp and a controller class, deployed in a tomcat server. The setup works fine for multiple requests. I have named the controller class as com.mypackage.mvcController. Now I used jvisualvm to find the number of instances this particular controller class is created. It shows 2. Why number of instances of this particular controller bean is two? By default spring beans are singleton. Of course here the instances does not vary with multiple requests, but