update 优化 SSE 心跳检测逻辑，增强连接管理与异常处理

ruoyi-common/ruoyi-common-sse/src/main/java/org/dromara/common/sse/core/SseEmitterManager.java

@@ -1,5 +1,6 @@
 package org.dromara.common.sse.core;
 
+import cn.hutool.core.collection.CollUtil;
 import cn.hutool.core.map.MapUtil;
 import lombok.extern.slf4j.Slf4j;
 import org.dromara.common.core.utils.SpringUtils;
@@ -8,6 +9,9 @@ import org.dromara.common.sse.dto.SseMessageDto;
 import org.springframework.web.servlet.mvc.method.annotation.SseEmitter;
 
 import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ScheduledExecutorService;
@@ -116,19 +120,38 @@ public class SseEmitterManager {
      * SSE 心跳检测，关闭无效连接
      */
     public void sseMonitor() {
-        log.info("开始 SSE 心跳");
-        USER_TOKEN_EMITTERS.forEach((userId, map) ->
-            map.entrySet().removeIf(e -> {
+        final SseEmitter.SseEventBuilder heartbeat = SseEmitter.event().comment("heartbeat");
+        // 记录需要移除的用户ID
+        List<Long> toRemoveUsers = new ArrayList<>();
+
+        USER_TOKEN_EMITTERS.forEach((userId, emitterMap) -> {
+            if (CollUtil.isEmpty(emitterMap)) {
+                toRemoveUsers.add(userId);
+                return;
+            }
+
+            emitterMap.entrySet().removeIf(entry -> {
                 try {
-                    e.getValue().send(SseEmitter.event().comment("heartbeat"));
+                    entry.getValue().send(heartbeat);
                     return false;
                 } catch (Exception ex) {
-                    log.warn("心跳失败，移除连接: userId={}, token={}", userId, e.getKey());
-                    e.getValue().complete();
-                    return true;
+                    try {
+                        entry.getValue().complete();
+                    } catch (Exception ignore) {
+                        // 忽略重复关闭异常
                     }
-            })
-        );
+                    return true; // 发送失败 → 移除该连接
+                }
+            });
+
+            // 移除空连接用户
+            if (emitterMap.isEmpty()) {
+                toRemoveUsers.add(userId);
+            }
+        });
+
+        // 循环结束后统一清理空用户，避免并发修改异常
+        toRemoveUsers.forEach(USER_TOKEN_EMITTERS::remove);
     }
 
     /**