Portal | Manuals | References | Downloads | Info | Programs | JCLs | Master the Mainframes
IBM Mainframe Computers Forums Index
 
Register
 
IBM Mainframe Computers Forums Index Mainframe: Search IBM Mainframe Forum: FAQ Memberlist Usergroups Profile Log in to check your private messages Log in
 

 

How to decrease the execution time of a Job

 
Post new topic   Reply to topic    IBMMAINFRAMES.com Support Forums -> JCL & VSAM
View previous topic :: :: View next topic  
Author Message
Husna

New User


Joined: 02 Jun 2006
Posts: 49

PostPosted: Mon Jul 17, 2006 9:53 am    Post subject: How to decrease the execution time of a Job
Reply with quote

I have a Job...Which will take 10 hrs to execute. Now, my requirement is to execute this job in an hour. How can I do the same without using any class changes (Prioriy also)?

Any one of you please let me know the solution for this?

Awaiting your reply.
Back to top
View user's profile Send private message

Bharanidharan

New User


Joined: 20 Jun 2005
Posts: 86
Location: Chennai, India

PostPosted: Mon Jul 17, 2006 12:45 pm    Post subject: Re: How to decrease the execution time of a Job
Reply with quote

The time a job takes to complete may depend on many parameters. I could think of these:
1. Type and volume of business processing - what is the number of records that get processed.
2. Timing at which the job runs - at what time the job is presented to JES (I assume that the duration of 10 hours you mentioned is the time from which you submitted the job till your job gets completed).
3. How many external connectivities your job handles & how efficient is your VTAM; these may prolong your job's completion time.
4. Resource contention and deadlocks.

If you feel that these factors are constants and have no effect on your process, can you expand your question a bit? Is it a hypothetical question or is it real-time? If it's latter, where do you face this?
Back to top
View user's profile Send private message
Hanfur

Active User


Joined: 21 Jun 2006
Posts: 104

PostPosted: Mon Jul 17, 2006 12:54 pm    Post subject: Hi
Reply with quote

Check the shops available job classes first ,and run in high priority class.

If VSAM processing is there try to implement buffers for reducing processing time.

If its Batch db2 prog which takes more time you have to explain the SQL qeeries to fine tune it as per shops standard.

-Han.
Back to top
View user's profile Send private message
pbgunasekar

New User


Joined: 28 May 2005
Posts: 26
Location: Chennai

PostPosted: Mon Jul 17, 2006 3:34 pm    Post subject: Re: How to decrease the execution time of a Job
Reply with quote

try to avoid taking backups of Master VSAM files more times.

regards,
guna
Back to top
View user's profile Send private message
GlobalGyan

New User


Joined: 31 Jan 2006
Posts: 28

PostPosted: Mon Jul 17, 2006 3:46 pm    Post subject:
Reply with quote

My team had done something like this a year back for a project. A daily job was running for about 4 hours and the req was to reduce it at least by 40%. LIke Bharanidharan pointed out in #1, we had looked into the records that were being processed. After some analysis found that the number of records processed was too high and also the daily input feed to the job was a big one with verry less changes in it the next day. So we wrote a program that would determine what needs to be processed and what does not need to be processed. After writing a simple cobol program, the job time was reduced to 20 mins! from 240 mins to 20 mins :-)

-GlobalGyan
Back to top
View user's profile Send private message
parikshit123

Active User


Joined: 01 Jul 2005
Posts: 269
Location: India

PostPosted: Fri Jul 21, 2006 12:42 pm    Post subject:
Reply with quote

Hi,

you might like to use STROBE to analyze which part of your program is taking more time to execute?

There are n number of factors that effects the efficiency of the code. you need to analyze the statistics of previous runs of the program and try to find out optimization opportunity and implement it!

Good luck man. Its a very painful task I believe. But greatly rewarding as well icon_smile.gif

Thanks,
Parikshit.
Back to top
View user's profile Send private message
MCEVOY

New User


Joined: 21 Nov 2005
Posts: 18

PostPosted: Fri Jul 21, 2006 2:31 pm    Post subject: Re: How to decrease the execution time of a Job
Reply with quote

Without knowing more about your job, it is difficult to offer help here.
My experience with such long running jobs is that they often involve a lot of I/O, which is very time-consuming.
You can reduce the time spent on I/O in a number of ways, but the following are fruitful approaches to pursue:
* Ensure that the blocksizes for your files are large (full-track or half-track). Smaller blocksizes imply smaller buffers and more excps to read/write.
* For really large files, code BUFFNO= to get more buffers. The default is 5, but more can help speed things up.
* For files that are passed within the job but not needed outside it, use UNIT=VIO. This creates the file in memory but not on disk (apart from paging), thereby avoiding I/O altogether.
Finally, the recommendation to use STROBE to analyse where the time is being spent is good advice. You may need to get your application support team to do this for you. You may discover that there are radical improvements that can be made to the logic.
If you are processing DB/2 tables, ensure that your tables have been Reorg'ed and your Plans rebound. Use the Explain command to examine the access paths. You might be dismayed to discover that your Select Statements are resulting in a Tablespace Scan every time. This can often happen with Plans which are bound for new tables which may be empty on first implementation and it makes sense to do a Tablespace Scan. However, when the data builds up, this becomes outrageously expensive.
Good luck.
Back to top
View user's profile Send private message
Ravi Rao

New User


Joined: 28 Feb 2006
Posts: 3

PostPosted: Sun Jul 23, 2006 9:52 pm    Post subject: Re: How to decrease the execution time of a Job
Reply with quote

HI,

There can many reasons for the job to run so long.
It would be good if you could analyze what programs the job is executing and see how the data is being accessed off files from the JCL.
Maybe the program is opening and closing files for each record that is being processed. You would have to look at reducing I/O for improving the processing time.
Back to top
View user's profile Send private message
View previous topic :: :: View next topic  
Post new topic   Reply to topic    IBMMAINFRAMES.com Support Forums -> JCL & VSAM All times are GMT + 6 Hours
Page 1 of 1

 

Search our Forum:

Similar Topics
Topic Author Forum Replies Posted
No new posts Date and time format in CICS Chandru3183 CICS 2 Sat Mar 18, 2017 12:46 pm
No new posts How to get current date -1 and curren... murali.andaluri DFSORT/ICETOOL 3 Wed Mar 08, 2017 2:09 pm
No new posts CICS transaction slow response time vasanthz All Other Mainframe Topics 3 Thu Jan 19, 2017 1:31 am
No new posts DD DUMMY & CPU TIME Nileshkul Testing & Performance analysis 16 Mon Dec 19, 2016 11:35 pm
This topic is locked: you cannot edit posts or make replies. Get a job submitted itself every time... arunsoods JCL & VSAM 3 Tue Nov 22, 2016 4:05 pm


Facebook
Back to Top
 
Mainframe Wiki | Forum Rules | Bookmarks | Subscriptions | FAQ | Tutorials | Contact Us