Common Reasons for Out Of Memory Errors

Out Of Memory error can happen due to following reasons:

• Garbage Collection Issues
• Orphaned Class loaders
  • Thread context classloader
  • new Thread()
  • Dangling thread
• Classes with following references
  • static variables
  • SQL Driver
  • Commons logging
  • java.util.logging.Level
  • Bean util
    • Details

etc..

We can analyze the problem(s) associated with such errors at application level by having GC details and/or heap dump

• -verbose:gc with -XX:+PrintGCDetails for observing GC model for tuning or altering suitable GC for the application
• -XX:+HeapDumpOnOutOfMemoryError
• -Xrunhprof:heap=dump,format=b
• jmap -dump:format=b,file=heap.bin <pid>
  

Analyze heap dump using Jhat

• jhat -J-mx1024m heap.bin
• http://localhost:7000
• Using built-in or custom queries to narrow down leak suspects
• Identify an object or class in the application
• List reference chains