JVM Performance

Tuning

Notes from [1]

• Biggest contributor to latency is the Garbage Collector
• Areas of Tuning : Memory, Lock Contention, CPU Usage, I/O
• Areas of Memory Tuning:
  • Memory footprint tuning
  • Allocation rate tuning
  • GC tuning

Memory footprint tuning

• It's all about ensuring that the GC has less work to do
• One of the classic symptoms is the OutOfMemoryError
• Why ? It can be too much data, or the data representation is "fat", or there is a memory leak in the app code
• What is too much data ?
• Look at the GC logs. Turn on the verbosegc option
• Look at the Full GC messages : [Full GC $before->$after($total), $time secs]
• If more memory can be added, add it.
• Do we actually need ALL that data in memory, consider using techniques such as LRU cache & Soft References