CF/U5 Topic 2 Batch Processing
Batch processing is a technique in which an Operating System collects the programs and data together in a batch before processing starts. An operating system does the following activities related to batch processing:
- The OS defines a job which has predefined sequence of commands, programs and data as a single unit.
- The OS keeps a number a jobs in memory and executes them without any manual information.
- Jobs are processed in the order of submission, i.e., first come first served fashion.
- When a job completes its execution, its memory is released and the output for the job gets copied into an output spool for later printing or processing.
Batch processing is a technique of processing data that occur in one large group instead of individually. Batch processing is usually done to help conserve system resources and allow for any modifications before being processed. For example, a banks will batch process all their transactions once every hour instead of processing each transaction immediately. Another example, is the Microsoft Outlook e-mail program, which will keep all your e-mails in an Outbox that is processed every few minutes allowing you to edit or delete before sending.
Batch jobs can be stored up during working hours and then executed during the evening or whenever the computer is idle. Batch processing is particularly useful for operations that require the computer or a peripheral device for an extended period of time. Once a batch job begins, it continues until it is done or until an error occurs. Note that batch processing implies that there is no interaction with the user while the program is being executed.
An example of batch processing is the way that credit card companies process billing. The customer does not receive a bill for each separate credit card purchase but one monthly bill for all of that months purchases. The bill is created through batch processing, where all of the data are collected and held until the bill is processed as a batch at the end of the billing cycle.
- Batch processing takes much of the work of the operator to the computer.
- Increased performance as a new job get started as soon as the previous job is finished, without any manual intervention.
- Difficult to debug program.
- A job could enter an infinite loop.
- Due to lack of protection scheme, one batch job can affect pending jobs.