Heap Dumps

A heap dump is a snapshot of the memory of a Java process at a specific point in time. It contains information about the Java objects that are in the heap memory, including their values and references to other objects. Heap dumps are primarily used for diagnosing memory leaks and performance issues in Java applications.

Key Reasons:

• Identify memory leaks by analyzing object retention.
• Monitor memory usage trends over time.
• Debug performance issues related to memory consumption.
• Understand object allocation and references.

Methods to Capture Heap Dumps:

1. Using jmap command:

jmap -dump:format=b,file=heapdump.hprof 

2. Using VisualVM:

Connect to the Java process using VisualVM, then navigate to the Monitor tab and click on "Heap Dump".

3. Using JVM options:

-XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/path/to/dump

After taking a heap dump, you can analyze it using tools like:

• MAT (Memory Analyzer Tool)
• VisualVM
• JProfiler

These tools can help you find memory leaks, identify large objects, and analyze the object graph.

To effectively use heap dumps for debugging, consider the following best practices:

• Regularly monitor heap usage in production environments.
• Take heap dumps during peak load and in case of OutOfMemoryError.
• Automate heap dump collection using JVM flags.
• Analyze heap dumps promptly to avoid accumulating issues.