Spring Application Optimizations:
@Async, use WebFlux’s WebClient for inter-service REST API callsJpaRepository, CrudRepository), implement caching, connection pooling,If anything goes wrong, debug using Actuator /metrics and Prometheus metrics stats.
Async processing in Spring Boot: we can use @Async annotation provided in Spring Boot instead of writing our own CompletableFutures everytime. notes
List all beans in a Spring Boot application:
@Autowired
private ApplicationContext applicationContext; // this contains every info about the app
public void listBeans{
for(String beanName : applicationContext.getBeanDefinitionNames()){
System.out.println(beanName);
}
}
Alternatively, actuator’s /beans endpoint can also list all beans, need to expose it first though.
YAML vs Properties: YAML is cleaner and structured, properties is simple and verbose. YAML files cannot be loaded by using the @PropertySource annotation so that’s a negative.
How to disable a specific Auto-Configuration?: find out the configuration class that configures the functionality and use exclude property in main class annotation.
@SpringBootApplication(exclude = {"DataSourceAutoConfiguration.class"})
public class MyApplication{
public static void main(String[] args){
SpringApplication.run(MyApplication.class, args);
}
}
Override a method on a class imported from JAR dependency: create a subclass and override the method (overrides on parent class ref too) and declare a custom bean of original type in a config class with the same name @Bean("") or use @Primary. We should try to avoid changing code too much here since original class maybe autowired at multiple places in the code hence @Qualifier isn’t a good solution here.
// original class autowired in multiple places in existing code
@Autowired
OriginalClass originalClass;
// original class bean
@Component
public class OriginalClass {
@Override
public void methodToOverride() {
System.out.println("Original implementation");
}
}
// create a custom class
public class CustomClass extends OriginalClass {
@Override
public void methodToOverride() {
System.out.println("Custom implementation");
}
}
// config class with bean override
@Configuration
public class CustomConfiguration {
@Bean("originalClass") // same name as the original class (bean overriding)
@Primary // alternatively we can mark it as primary (better way; bean selection)
public OriginalClass customClass() {
return new CustomClass();
}
}
// ensure proper component scan in Spring so that our custom bean is picked up
// our custom bean will override the original bean from the JAR if it has the same name
// alternatively if we mark it using the @Primary annotation, it ensures that if there are multiple beans of the same type, Spring will prefer the custom bean even if names are diff
Scaling for high traffic:
Calling other services: be async (use WebFlux’s WebClient), implement circuit breaker, rate limit with exponential backoff, and cache responses to reduce network requests.
Event-driven architecture: for intra-app event driven communication we can use events API provided in Spring. notes
Soft Delete: mark rows as delted = true in a boolean column. On reads, filter out these marked rows from the output.