[HSC-423] admin log-feature dispatch rejection 정책 변경 및 reject 계측 추가

src/main/java/site/holliverse/customer/application/usecase/log/UserLogService.java

@@ -8,6 +8,7 @@
 import org.springframework.context.annotation.Profile;
 import org.springframework.kafka.core.KafkaTemplate;
 import org.springframework.scheduling.annotation.Async;
+import org.springframework.core.task.TaskRejectedException;
 import org.springframework.stereotype.Service;
 
 import com.github.f4b6a3.tsid.Tsid;
@@ -120,11 +121,17 @@ private void sendAdminTarget(Long memberId, UserLogRequest request) {
             return;
         }
 
-        adminLogFeatureDispatchService.dispatch(
-                memberId,
-                eventName,
-                request.timestamp()
-        );
+        try {
+            adminLogFeatureDispatchService.dispatch(
+                    memberId,
+                    eventName,
+                    request.timestamp()
+            );
+            customerMetrics.recordAdminLogFeatureDispatch("enqueued");
+        } catch (TaskRejectedException e) {
+            log.warn("[UserLog] Admin log-feature dispatch rejected. memberId={}, eventName={}", memberId, eventName);
+            customerMetrics.recordAdminLogFeatureDispatch("rejected");
+        }
     }
 
     /**

src/main/java/site/holliverse/shared/config/runtime/CustomerRuntimeInfraConfiguration.java

@@ -41,7 +41,7 @@ public ThreadPoolTaskExecutor adminLogFeatureTaskExecutor() {
         executor.setMaxPoolSize(16);
         executor.setQueueCapacity(512);
         executor.setThreadNamePrefix("admin-log-feature-");
-        executor.setRejectedExecutionHandler(new java.util.concurrent.ThreadPoolExecutor.CallerRunsPolicy());
+        executor.setRejectedExecutionHandler(new java.util.concurrent.ThreadPoolExecutor.AbortPolicy());
         executor.initialize();
         return executor;
     }

src/main/java/site/holliverse/shared/monitoring/CustomerMetrics.java

@@ -82,4 +82,12 @@ public void stopAdminLogFeatureDuration(Timer.Sample sample, String result) {
                 .tag("result", result)
                 .register(meterRegistry));
     }
+
+    public void recordAdminLogFeatureDispatch(String result) {
+        Counter.builder("holliverse.userlog.admin_log_feature.dispatch")
+                .description("Admin log-feature async dispatch enqueue results")
+                .tag("result", result)
+                .register(meterRegistry)
+                .increment();
+    }
 }