如何在时间窗口中运行开放式石英作业，然后用弹簧干净地退出

Question

I have a quartz job that updates some records in a database. Since the number of records to update is huge, it will do it in batches of 100 for a period of 2 hours every night between 1 and 3 AM.

So if it is processing a job when the 3 AM deadline reaches, I would like it to finish processing the current batch of 100 records and then exit cleanly. How can this be achieved? Can it be done using a cron expression alone or is there some mechanism to achieve this graceful shutdown?

I am using spring's SchedulerFactoryBean and MethodInvokingJobDetailFactoryBean classes to configure the job in my application context xml.

Some pseudo code of my job implementation method.

public void updateRecords()
{
    while(true) // i need to replace true with some other logic to exit from loop at scheduled time.
    {
        // 1. select 100 records
        // 2. update 100 records
        // 3. commit
    }
}

Answer 1

When you run the updateRecords, store the System.currentTimeMillis and see if the time has exceeded that time + 2*60*60*1000 ms in the while loop.

public void updateRecords()
{
    long jobStartedAt = System.currentTimeMillis();
    long twoHoursLater = jobStartedAt + 2 * 60 * 60 * 1000; //2 hours, 60 minutes/hour, 60 seconds/minute, 1000 ms/second
    while(System.currentTimeMillis() < twoHoursLater) 
    {
        // 1. select 100 records
        // 2. update 100 records
        // 3. commit
    }
}

Also: Depending on your database properties, 100 jobs in a batch could be a bit to small to efficient. Don't be afraid to try larger batches.

And if the jobs takes very long it could be because of heavy indexing. If you have the possibility, drop the indexes before doing large scale (dumb) batching and rebuild them afterwards, if they are not explicitly needed for the batch processing. Every update of indexes can render many more diskwrites than the single change of a record.