JProfiler | 易学教程

How can I figure out what is holding on to unfreed objects?

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问题 One of our programs is sometimes getting an OutOfMemory error on one user's machine, but of course not when I'm testing it. I just ran it with JProfiler (on a 10 day evaluation license because I've never used it before), and filtering on our code prefix, the biggest chunk both in total size and number of instances is 8000+ instances of a particular simple class. I clicked the "Garbage Collect" button on JProfiler, and most instances of other classes of ours went away, but not these particular

Identifying lambdas in stacktrace in Java 8

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问题 I am trying to profile a Java application that uses lambdas using JProfiler. I am having trouble identifying, which lambda the profiler is showing as a hotspot: I would appreciate any help on understanding the format of the stack trace involving lambdas like "edu.indiana.soci.spidal.vectorclass.lambda$PairwiseThread_SecDrv$23" Thank you! 回答1: Unfortunately, there is no direct way to identify the lambda because lambdas by nature have no name. At runtime, lambdas are currently implemented with

How to connect JProfiler to an application running on localhost?

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问题 I have an application running on my localhost and I want to profile the application to see how can I enhance the performance of the application. I am doing the setup steps as defined but it is not able to connect to localhost server, is there a proper step by step guideline available on how to: Configure JProfiler to work with application running on localhost? How to profile and what areas to look for while profiling for an application? Configure JProfiler with Eclipse IDE, right now am able

JVM总结-OutOfMemoryError异常

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在JVM规范中，除了程序计数器，虚拟机内存的其他几个运行区域都有可能发生OutOfMemoryError异常。 Java堆溢出： Java堆是用来存储对象实例，只要不停地创建对象实例，并且让GC ROOTS到对象之间有可达路径来避免垃圾回收机制清除这些对象，当对象数量达到最大堆的容量限制就会产生内存溢出的异常。通过设置JVM参数-XX:+HeapDumpOnOutOfMemoryError可以让JVM在发生内存泄露异常Dump出当前内存堆转储快照方便后面分析。默认情况下，堆内存快照会保存在JVM的启动目录下名为java_pid<pid>.hprof 的文件里（在这里<pid>就是JVM进程的进程号）当堆内存溢出时，会在异常信息后提示Java heap space 使用内存映像分析工具进行分析，判断是内存溢出还是内存泄露 1、内存泄露：通过工具查看泄露对象到GC ROOTS引用链。就可以找到泄露对象是通过怎样的路径与GC ROOTS相关联，导致垃圾收集器无法自动回收他们 2、内存溢出：检查虚拟机的堆参数，看是否还可以调大，从代码上检查某些对象生命周期过长，持有时间过长的情况。例子：使用JProfiler 1、打开快照文件 2、查看占用内存较大的对象 2、查看该对象通过怎样的路径与gc roots相关联虚拟机栈和本地方法栈溢出