Analyzing Large Java Heap Dumps Using Memory Analyzer CLI

Luke Hebert

- 2 minutes read - 242 words

When you need to analyze a 30 or 40 GB heap dump, the MAT UI will most likely choke on the file size. The Memory Analyzer CLI, however, handles those monsters just fine on Linux. Below is the setup and the exact commands you need to parse a multi-gigabyte dump and produce shareable HTML reports.

Prerequisites

  • Make sure you have enough physical or virtual (VM) memory available, at least equal to the size of the dump file, so the analyzer runs smoothly.
  • Download the tool from Eclipse MAT.
  • Confirm you have the necessary privileges or access to the Linux system.

Steps to Follow

  1. Unzip the downloaded Memory Analyzer tool:

    unzip MemoryAnalyzer-1.7.0.20170613-linux.gtk.x86_64.zip

  2. Enter the extracted directory:

    cd mat

  3. Run the command to start the dump analyzer:

    ./ParseHeapDump.sh /dumps/heap.date.bin -vmargs -Xmx40g -XX:-UseGCOverheadLimit
    • -Xmx40g allocates 40 GB of memory to the process. Adjust this value to match your dump size.
    • /dumps/heap.date.bin is the full path to your dump file. Replace it with your actual file path.

  4. The command will take time proportional to the dump size. When it finishes, index files are generated in the same directory as your dump file.

  5. Generate the HTML report:

    ./ParseHeapDump.sh /dumps/heap.date.bin org.eclipse.mat.api:suspects

    org.eclipse.mat.api:suspects specifies the report type. Other available report types include:

    org.eclipse.mat.api:suspects
org.eclipse.mat.api:overview
org.eclipse.mat.api:top_components

  6. The command produces a jvm_suspects.zip file containing the HTML reports.

  7. Share those HTML reports with your team via SCP, email, FTP, or any other method that works for you.