spring quartz使用多線程並發“陷阱”（轉）

spring quartz使用多線程並發“陷阱”

博客分類：

 
• Java

多線程 quartz Spring thread Bean 

定義一個job：ranJob，設置每秒執行一次，設置不允許覆蓋並發執行

 

<bean id="rankJob" class="com.chinacache.www.logstat.job.RankJob" />
<bean id="rankJobDetail"
    class="org.springframework.scheduling.quartz.MethodInvokingJobDetailFactoryBean">
    <property name="targetObject" ref="rankJob" />
    <property name="targetMethod" value="execute" />
    <property name="concurrent" value="<span style="color: #ff0000;"><strong>false</strong></span>" />
</bean>
<bean id="rankJobTrigger" class="org.springframework.scheduling.quartz.SimpleTriggerBean">
    <property name="jobDetail" ref="rankJobDetail" />
    <!-- 單位 ms，半小時 1800000 ms -->
    <property name="repeatInterval" value="<span style="color: #ff0000;"><strong>1000</strong></span>" />
</bean>

 

job代碼：

System.out.println("Start job");
ExecutorService exec = Executors.newFixedThreadPool(1);

Thread thread = new Thread(new Runnable() {
    @Override
    public void run() {
        System.out.println("thread start");
        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        System.out.println("thread end");
    }
});
exec.execute(thread);
System.out.println("end job");

 

程序輸出結果：

Start job
end job
<span style="color: #ff0000;"><strong>thread start</strong></span>
Start job
end job
thread start
Start job
end job
thread start
Start job
end job
thread start
<strong><span style="color: #ff0000;">thread end</span></strong>

 

從結果可以看到，job的並發覆蓋配置似乎根本沒有生效，原因是：job沒有關注多線程執行情況

修改job代碼，添加如下代碼在job訪問最后，線程處理完job才結束，

 

while (!exec.isTerminated()) {
    // 等待所有子線程結束，才退出主線程
}

 

修改代碼后程序結果：

Start job
thread start
thread end

 

可以看到job始終沒有結束，說明ExecutorService始終沒有終止，看看文檔，加入shutdonw()方法，job所有代碼如下：

public void execute() throws InterruptedException {
    System.out.println("Start job");
    ExecutorService exec = Executors.newFixedThreadPool(1);

    Thread thread = new Thread(new Runnable() {
        @Override
        public void run() {
            System.out.println("thread start");
            try {
                Thread.sleep(3000);
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            System.out.println("thread end");
        }
    });
    exec.execute(thread);
    exec.shutdown();
       while (!exec.isTerminated()) {
           // 等待所有子線程結束，才退出主線程
       }
    System.out.println("end job");
}

 

打印結果如下：

 

Start job
thread start
thread end
end job

Start job
thread start
thread end
end job

Start job
thread start
thread end
end job

 

 

OK，至此spring quartz多線程並發問題解決。回顧下，我們要使用isTerminated()方法等多線程結束后在結束job；多線程任務派發結束后，要使用shutdown()方法順序關閉線程（等待正在執行任務，不接受新任務）