From c00a2995c88b5028c42bd9a8d3c80bf3c3eb9142 Mon Sep 17 00:00:00 2001
From: xuxueli <931591021@qq.com>
Date: Thu, 18 Jul 2019 21:54:45 +0800
Subject: [PATCH] =?UTF-8?q?=E4=BB=BB=E5=8A=A1=E8=A7=A6=E5=8F=91=E7=BB=84?=
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---
 doc/XXL-JOB官方文档.md                    |  2 +-
 .../admin/core/thread/JobScheduleHelper.java  | 24 ++++++++++++-------
 2 files changed, 16 insertions(+), 10 deletions(-)

diff --git a/doc/XXL-JOB官方文档.md b/doc/XXL-JOB官方文档.md
index 3774b334..12b98239 100644
--- a/doc/XXL-JOB官方文档.md
+++ b/doc/XXL-JOB官方文档.md
@@ -1517,7 +1517,7 @@ Tips: 历史版本(V1.3.x)目前已经Release至稳定版本, 进入维护阶段
 - 6、登录界面取消默认填写的登录账号密码；
 - 7、[ING]cron在线生成工具；
 - 8、[ING]任务、执行器数据全量本地缓存；新增消息表广播通知；
-- 9、[ING]任务触发组件优化，常规1s预加载一次，轮空时主动休眠4s；
+- 9、任务触发组件优化，常规1s预加载一次，预加载轮空时主动休眠4s，降低加载频率以及对DB压力；
 - 10、注册监控线程优化，降低死锁几率；
 - 11、调度组件优化：针对永远不会触发的Cron禁止配置和启动；任务Cron最后一次触发后再也不会触发时，比如一次性任务，主动停止相关任务；
 - 12、任务列表交互优化，支持查看任务所属执行器的注册节点；
diff --git a/xxl-job-admin/src/main/java/com/xxl/job/admin/core/thread/JobScheduleHelper.java b/xxl-job-admin/src/main/java/com/xxl/job/admin/core/thread/JobScheduleHelper.java
index 89c5e6d0..bd9a5128 100644
--- a/xxl-job-admin/src/main/java/com/xxl/job/admin/core/thread/JobScheduleHelper.java
+++ b/xxl-job-admin/src/main/java/com/xxl/job/admin/core/thread/JobScheduleHelper.java
@@ -52,9 +52,10 @@ public class JobScheduleHelper {
                 Connection conn = null;
                 while (!scheduleThreadToStop) {
 
-                    // 扫描任务
+                    // Scan Job
                     long start = System.currentTimeMillis();
                     PreparedStatement preparedStatement = null;
+                    boolean preReadSuc = true;
                     try {
                         if (conn==null || conn.isClosed()) {
                             conn = XxlJobAdminConfig.getAdminConfig().getDataSource().getConnection();
@@ -154,6 +155,8 @@ public class JobScheduleHelper {
                                 XxlJobAdminConfig.getAdminConfig().getXxlJobInfoDao().scheduleUpdate(jobInfo);
                             }
 
+                        } else {
+                            preReadSuc = false;
                         }
 
                         // tx stop
@@ -187,14 +190,17 @@ public class JobScheduleHelper {
                     }
                     long cost = System.currentTimeMillis()-start;
 
-                    // next second, align second
-                    try {
-                        if (cost < 1000) {
-                            TimeUnit.MILLISECONDS.sleep(1000 - System.currentTimeMillis()%1000);
-                        }
-                    } catch (InterruptedException e) {
-                        if (!scheduleThreadToStop) {
-                            logger.error(e.getMessage(), e);
+
+                    // Wait seconds, align second
+                    if (cost < 1000) {  // scan-overtime, not wait
+                        try {
+                            // pre-read success, exist job in 5s, wait 1s;
+                            // pre-read fail, no exist job in 5s, wait 1s
+                            TimeUnit.MILLISECONDS.sleep((preReadSuc?1000:4000) - System.currentTimeMillis()%1000);
+                        } catch (InterruptedException e) {
+                            if (!scheduleThreadToStop) {
+                                logger.error(e.getMessage(), e);
+                            }
                         }
                     }