How do you create a high-performance system that requires minimal garbage collection?

A high-performance system with minimal garbage collection should be designed to reduce object allocation, limit memory churn, and efficiently utilize available resources. The goal is to decrease GC frequency and pause times, resulting in predictable performance and low latency, especially in systems such as trading platforms, gaming engines, and real-time applications.

Key Points: • Minimize object creation by reusing objects, using object pools where appropriate, and avoiding unnecessary temporary objects. • Prefer primitive types and efficient data structures to reduce memory overhead and heap allocations. • Choose an appropriate garbage collector such as ZGC, Shenandoah, or G1 GC and tune JVM parameters based on application requirements.

Example: In a high-frequency trading application processing thousands of transactions per second, creating new objects for every transaction can generate excessive garbage. Reusing transaction objects from a pool reduces memory allocations and minimizes GC activity, resulting in lower latency.

Code Example:

import java.util.ArrayDeque;
import java.util.Queue;

class Transaction {

    private String id;

    public void setId(String id) {

        this.id = id;
    }
}

class TransactionPool {

    private final Queue<Transaction> pool =
            new ArrayDeque<>();

    public Transaction borrowObject() {

return pool.isEmpty()

                ? new Transaction()
                : pool.poll();
    }

    public void returnObject(
            Transaction transaction) {

        pool.offer(transaction);
    }
}

Best Practices: • Reuse frequently created objects when justified. • Avoid excessive String concatenation in loops. • Use StringBuilder for mutable string operations. • Prefer primitive collections when possible. • Use off-heap storage for large datasets when appropriate. • Remove unnecessary object references promptly. • Profile allocation rates using JFR, VisualVM, or JProfiler. • Tune heap size and select a suitable GC strategy.

Interview Tip: A concise interview answer is: To minimize garbage collection, I reduce object creation, reuse objects when appropriate, choose efficient data structures, eliminate memory leaks, and tune the JVM with a suitable garbage collector such as G1 GC, ZGC, or Shenandoah. Profiling memory allocation patterns helps identify hotspots and further optimize performance.