The best way to learn anything is to actually do it. Just with the information you have learnt so far, you can figure out almost all usual memory issues. In order to fully see the power of this tool, you really have to experience it yourself. The resulting screen shows several useful metrics.Īnother useful view is the ‘dominator tree’ where you can see the biggest objects living inside the heap. Once loaded, you are given option to open few types of reports. Note: If loading the heap dump file fails, you may have to increase the Max heap for MAT by updating –Xmx in MemoryAnalyzer.ini fileĭepending on the size of the heap dump file, it will take a bit to load the heap dump. Unzip the download and execute MemoryAnalyzer.exe (windows) under the ‘mat’ directory.Opening screen looks like below:Ĭlick on File-> Open Heap dump and choose your heap dump file (typically HPROF format) Note that this option is verified to work on Oracle Hotspot JVM only.Įclipse MAT can be downloaded as a standalone client from Further you can configure the Application server to automatically perform a heap dump when an ‘out of memory’ error is encountered (XX:-HeapDumpOnOutOfMemoryError). You can also use the command ‘jmap’ to create heap dump. Earlier you saw visualvm can create a heap dump for you through the visualvm interface.

For example, if you are running IBM WebSphere, you could use a wsadmin script to invoke heap dump. Now, this varies from application to application. And how do you analyze the heap dump? By using the all-powerful Eclipse Memory Analyzer (MAT)īefore we begin using MAT, how do you capture heap dump? How do you get an insight into what is in the Heap? By analyzing a Heap dump. Mind you this can run into hundreds of millions in numbers. We are literally talking about all those java objects that are in the heap.

In your Application support/Developer Journey, you will definitely come across a time where you will want to really dive into the Java heap and see what is filling up the memory.

Download eclipse memory analyzer