[ISSUE-#4762] Naming health check thread num support user define it b…

…y self. (#4764)

* NAMING_HEALTH_EXECUTOR support user define it by self.

* promise less one thread to process the health check task.

naming/src/main/java/com/alibaba/nacos/naming/misc/GlobalExecutor.java

@@ -100,8 +100,9 @@ public class GlobalExecutor {
                     new NameThreadFactory("com.alibaba.nacos.naming.tcp.check.worker"));
 
     private static final ScheduledExecutorService NAMING_HEALTH_EXECUTOR = ExecutorFactory.Managed
-            .newScheduledExecutorService(ClassUtils.getCanonicalName(NamingApp.class), DEFAULT_THREAD_COUNT,
-                    new NameThreadFactory("com.alibaba.nacos.naming.health"));
+            .newScheduledExecutorService(ClassUtils.getCanonicalName(NamingApp.class),
+                    Integer.max(Integer.getInteger("com.alibaba.nacos.naming.health.thread.num", DEFAULT_THREAD_COUNT),
+                            1), new NameThreadFactory("com.alibaba.nacos.naming.health"));
 
     private static final ScheduledExecutorService RETRANSMITTER_EXECUTOR = ExecutorFactory.Managed
             .newSingleScheduledExecutorService(ClassUtils.getCanonicalName(NamingApp.class),
@@ -142,7 +143,7 @@ public static void scheduleMcpPushTask(Runnable runnable, long initialDelay, lon
     public static ScheduledFuture submitClusterVersionJudge(Runnable runnable, long delay) {
         return NAMING_TIMER_EXECUTOR.schedule(runnable, delay, TimeUnit.MILLISECONDS);
     }
-
+    
     public static void submitDistroNotifyTask(Runnable runnable) {
         DISTRO_NOTIFY_EXECUTOR.submit(runnable);
     }