Logger creation in classes in Spring Boot - Performance & Optimization

Performance: Logger creation in classes

MEDIUM IMPACT

This affects application startup time and memory usage due to logger instance creation in each class.

Creating a logger instance in every class for logging

Spring Boot

public class MyService {
    private static final Logger logger = LoggerFactory.getLogger(MyService.class);
    // reuse logger efficiently
}

// or use centralized logging configuration

Using static final logger per class avoids repeated creation and allows JVM to optimize logger reuse.

📈 Performance GainReduces memory overhead and startup time compared to dynamic or multiple logger creations.

Creating a logger instance in every class for logging

Spring Boot

public class MyService {
    private Logger logger = LoggerFactory.getLogger(MyService.class);
    // class code
}

// repeated in every class

Non-static logger field creates a reference per object instance, which can increase memory usage and slow startup if many instances exist.

📉 Performance CostAdds memory overhead proportional to number of instances; can increase startup time slightly.

Performance Comparison

Pattern	Memory Usage	Startup Impact	Reuse Efficiency	Verdict
Static final logger per class	Low (one instance per class)	Minimal	High (reused efficiently)	[OK] Good
Dynamic logger creation per method call	High (many instances)	Noticeable delay	Low (new instances each time)	[X] Bad

Rendering Pipeline

Logger creation happens during class loading and initialization, impacting JVM startup and memory allocation.

→Class Loading

→Memory Allocation

⚠️ BottleneckMemory Allocation during class initialization

Optimization Tips

1Always declare loggers as static final fields in each class.

2Avoid creating logger instances inside methods or dynamically at runtime.

3Use logger factories that cache logger instances to reduce overhead.

Performance Quiz - 3 Questions

What is the best practice for creating loggers in Spring Boot classes to optimize performance?

A Use a global logger instance for all classes

B Create a new logger instance every time a method is called

C Create a static final logger instance per class

D Create logger instances dynamically during runtime

DevTools: JVisualVM or Java Flight Recorder

How to check: Profile application startup and memory usage; look for logger instance counts and class initialization times.

What to look for: High memory usage or many logger instances indicate inefficient logger creation.