How to read a file in parallel using COBOL program?

haohao · Posted: Thu Mar 28, 2013 9:42 am

Hello all,

there is a scenario that need to read a file in parallel with cobol program.

If a file is already be opened and written info into it by one process, just like a system log file, is it possibol to open that file by another cobol batch program in share mode?

I just did a test, the batch job was hanging with a message of waiting for data set.

do you have the same requirement ever before? and does it can be achieved by any workaround?

Anuj Dhawan · Posted: Thu Mar 28, 2013 10:29 am

Hi - What is the access type for file or what kind of file you're referring here?

Nic Clouston · Posted: Thu Mar 28, 2013 2:57 pm

If the file is a sequential file then the program writing to it should have a DISP of NEW or OLD. Either implies exclusive use so another program cannot SHR. If the file is VSAM, on the other hand, it will depend on the share options specified for the VSAM file.

haohao · Posted: Thu Mar 28, 2013 3:39 pm

thanks a lot for your quick response

it doesn't matter use PS file or Vsam file, both are OK.

If use VSAM file, how to set the share optioin?

Robert Sample · Posted: Thu Mar 28, 2013 4:40 pm

You don't -- or at least should not -- determine VSAM file share options based upon a single situation; you must look at how the file is being used by the entire application. Depending upon the site standards and the application and the experience level of the developer, any SHROPTION (2,3) or (3,3) or (4,3) might be appropriate.

haohao · Posted: Fri Mar 29, 2013 5:52 am

OK, thanks a lot Robert, I will first have a test on it

Anuj Dhawan · Posted: Fri Mar 29, 2013 10:35 am

haohao · Posted: Fri Mar 29, 2013 11:03 am

I just tested with a PS file, first use edit mode open it in ISPF, and let another batch job open it with DISP=SHR mode. under that circumstance the batch job pending with waiting for data set.

dick scherrer · Posted: Fri Mar 29, 2013 6:51 pm

Hello,

Yup, exactly as intended. . .

Ed Goodman · Active Member Joined: 08 Jun 2011 Posts: 556 Location: USA

We have a system in place that lets programs each create their own flat file of messages. Then, at the end of batch, we gather them and copy them into a single file.

This is important for handling problems where a job abends and needs to restart. Any log messages since the last commit need to come out, so we can't share the files.