Java任务控制堆配置文件 [英] Java Mission Control Heap Profile

问题描述

我正在使用随Java 7u40提供的新Java Java任务控制分析器，并且我无法使用配置文件分配和收集对象统计信息。无论我做什么，我都无法在内存 - > 对象统计信息窗口中看到任何统计信息。

以下命令启动集合：

  jcmd< pid> JFR.start duration = 60s settings = profile filename = alloc-prof.jfr 
  

Java Mission Control文档没有提及启用对象分析的任何特定选项。我试图创建自己的配置文件并设置：

$ p $ < flag name =heap-statistics-enabledlabel =堆统计>真< /标志>
< flag name =allocation-profiling-enabledlabel =Allocation Profiling> true< / flag>


但是仍然没有收集对象统计信息。

解决方案

使用Mission Control中提供的模板管理器。

转到Windows - >模板管理器并导入模板并检查堆统计和分配分析，导出它。完成！

如果您想手动编辑jfc文件，那么知道控件元素内部的元素不会被JVM读取，元素，JMC使用它们来修改控件元素外部的参数（具有控件属性的元素）

手动编辑需要您修改以下内容：

设置java / object_alloc_in_new_TLAB为真

设置java / object_alloc_outside_TLAB为true

将vm / gc / detailed / object_count设置为true

请注意，有两个对象计数事件，其中object_count_after_gc会增加GC时间。如果你选择上面的那个，你会得到一个额外的GC每个记录块（这通常是足够的）

I am playing with the new Java Mission Control Profiler that is coming with the Java 7u40 and I cannot make it to profile allocation and collect object statistics. No matter what I do, I cannot see any statistics in the Memory -> Object Statistics window.

The following command starts the collection:

jcmd <pid> JFR.start duration=60s settings=profile filename=alloc-prof.jfr

The Java Mission Control documentation does not mention any specific options to enable object profiling. I have tried to create my own profile and set :

  <flag name="heap-statistics-enabled" label="Heap Statistics">true</flag>
  <flag name="allocation-profiling-enabled" label="Allocation Profiling">true</flag>

But still no Object Statistics are collected.

解决方案

Use the template manager that is available in Mission Control.

Go to Windows -> Template Manager and import the template and check Heap Statistics and Allocation Profiling, export it. Done!

If you want to edit the jfc-file manually, it can be good to know elements inside the control-element are not read by the JVM, i.e flag-element, They are used by JMC to modify the parameters outside the control element (the one with the control attribute)

A manual edit requires that you modify these:

set java/object_alloc_in_new_TLAB enabled to true

set java/object_alloc_outside_TLAB enabled to true

set vm/gc/detailed/object_count enabled to true

Note, there are two object count events, with object_count_after_gc you will increase GC times. If you pick the one above instead, you will get one additional GC per recording chunk (which is usually sufficient)

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