Using @Async annotation

- Changed synchronous mail transfer to asynchronous.

src/main/java/com/yam/app/account/infrastructure/MailManager.java

@@ -2,13 +2,14 @@ package com.yam.app.account.infrastructure;
 
 import com.yam.app.account.domain.RegisterAccountEvent;
 import org.springframework.beans.factory.annotation.Value;
+import org.springframework.scheduling.annotation.Async;
 import org.springframework.stereotype.Component;
 import org.springframework.transaction.event.TransactionalEventListener;
 import org.thymeleaf.TemplateEngine;
 import org.thymeleaf.context.Context;
 
 @Component
-final class MailManager {
+class MailManager {
 
     private final MailDispatcher mailDispatcher;
     private final TemplateEngine templateEngine;
@@ -21,6 +22,7 @@ final class MailManager {
         this.host = host;
     }
 
+    @Async
     @TransactionalEventListener
     public void handle(RegisterAccountEvent event) {
         var newAccount = event.getAccount();

src/main/java/com/yam/app/common/configuration/AsyncConfiguration.java

@@ -0,0 +1,28 @@
+package com.yam.app.common.configuration;
+
+import java.util.concurrent.Executor;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.scheduling.annotation.AsyncConfigurer;
+import org.springframework.scheduling.annotation.EnableAsync;
+import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
+
+@Slf4j
+@EnableAsync
+@Configuration
+public class AsyncConfiguration implements AsyncConfigurer {
+
+    @Override
+    public Executor getAsyncExecutor() {
+        var executor = new ThreadPoolTaskExecutor();
+        int processors = Runtime.getRuntime().availableProcessors();
+        log.info("processors count {}", processors);
+        executor.setCorePoolSize(processors);
+        executor.setMaxPoolSize(processors * 2);
+        executor.setQueueCapacity(50);
+        executor.setKeepAliveSeconds(60);
+        executor.setThreadNamePrefix("AsyncExecutor-");
+        executor.initialize();
+        return executor;
+    }
+}