Zero GC

• Use primitive type whenever possible
• Use mutable object whenever possible (e.g. High frequency data like book and order acknowledgement read from shared memory)
• Use object pool when object creation is inevitable
• LSB+MSB <=> UUID
• Avoid for-each on object collection
• Avoid stream API
• Avoid autoboxing

Concurrency

Volatile

• Basic - visibility/happen-before
• Cache coherence
• Memory barrier

Non-Blocking

• Optimistic Locking (aka. Optimistic Concurrency Control)
• CAS
• A-B-A Problem

CPU pinning

How to check

• ps
• lscpu (e.g. lscpu –all –parse=CPU,Socket)
• cat /proc/cmdline
• cat /etc/redhat-release
• jps
• jstack

Circular buffer

JIT

• Warmup
• Simple code

IPC

• Shared memory
• SBE (Binary)
• Protobuf (key-value)

JVM Parameters

-XX:MetaspaceSize=128m
-XX:MaxMetaspaceSize=256m
-XX:+UseNUMA (GC Heap Locality group)
-XX:-UseBiasdLocking
-XX:MaxGCPauseMillis=1
-XX:UnlockDiagnosticVMOptions
-XX:ComplieThreshold=1
-XX:+PrintCompilation
-XX:+PrintCodeCache
-XX:+PrintGCApplicationStoppedTime
-XX:+PrintGCApplicationConcurrentTime
-XX:+PrintSafepointStatistics

Profiling

JProfiler