topic Re: Need help in understanding Shared memory concept in Application Development and Automation Discussions

Need help in understanding Shared memory concept

Former Member — Wed, 18 Jun 2008 20:49:21 GMT

Hello everyone,

I am not able to understand Shared memory concept and how it works. Could you please provide me any links to tutorials or explain simply through this forum.

Thanks in advance.

Re: Need help in understanding Shared memory concept

Former Member — Wed, 18 Jun 2008 21:23:28 GMT

Please check this PDF under the link

https://admin.sdn.sap.com/irj/sdn/go/portal/prtroot/docs/library/uuid/900e3d9d-559e-2910-9dae-b132157a220f

http://help.sap.com/saphelp_nw04s/helpdata/en/c5/85634e53d422409f0975aa9a551297/content.htm

Thanks

Romit

Edited by: Romit Kewalramani on Jun 18, 2008 11:29 PM

Re: Need help in understanding Shared memory concept

Former Member — Thu, 19 Jun 2008 02:59:05 GMT

Hi,

Def:

In computer programming, shared memory is a method by which program processes can exchange data more quickly than by reading and writing using the regular operating system services. For example, a client process may have data to pass to a server process that the server process is to modify and return to the client. Ordinarily, this would require the client writing to an output file (using the buffers of the operating system) and the server then reading that file as input from the buffers to its own work space. Using a designated area of shared memory, the data can be made directly accessible to both processes without having to use the system services. To put the data in shared memory, the client gets access to shared memory after checking a semaphore value, writes the data, and then resets the semaphore to signal to the server (which periodically checks shared memory for possible input) that data is waiting. In turn, the server process writes data back to the shared memory area, using the semaphore to

indicate that data is ready to be read.

Refer the below link.

[http://searchsap.techtarget.com/tip/0,289483,sid21_gci1275261,00.html|http://searchsap.techtarget.com/tip/0,289483,sid21_gci1275261,00.html]

Reward if found helpful.

Regards,

Boobalan Suburaj

Re: Need help in understanding Shared memory concept

Former Member — Thu, 19 Jun 2008 03:03:59 GMT

Hi Karan,

Please check this link

SAP Memory Management

http://asfan.files.wordpress.com/2007/12/memorymanagement.ppt#279,1,Slide 1

http://searchsap.techtarget.com/generic/0,295582,sid21_gci1273431,00.html

Shared memory objects are ABAP Object Instances, which can be stored in the shared memory area on an application server. Instead of going to the database to retrieve the required data, the data is accessed through the shared memory, thereby providing faster data retrieval.

This shared memory area can be accessed by all of the ABAP programs running on that application server. Before the upgrade to SAP ERP 6.0, we use the EXPORT/IMPORT statements with the SHARED BUFFER or SHARED MEMORY extensions to access a similar memory buffer area. So what are the advantages of using this new functionality?

First, it is read access to shared memory without the need to copy it into user session memory. Technically, an application does a remote attach to the memory segment within shared memory and directly interacts with it.

Secondly, the new shared memory technique is implemented through ABAP Objects; therefore, you are provided with robust tools to interact with shared memory through code. Ultimately, you aren't just buffering raw sets of data; you're also providing a shared mechanism to access the business logic wrapped around this data.

There are also dedicated tools for the monitoring and administration of these shared areas and the objects within them. Transaction SHMM, for example, provides tools to monitor the size and number of objects within a shared area, as well as enabling administrators to force objects out of memory if necessary.

Best regards,

raam

Re: Need help in understanding Shared memory concept

Former Member — Thu, 19 Jun 2008 03:38:46 GMT

Hi,

refer to these links

https://www.sdn.sap.com/irj/sdn/go/portal/prtroot/docs/library/uuid/900e3d9d-559e-2910-9dae-b132157a220f

Re: Need help in understanding Shared memory concept

Former Member — Thu, 19 Jun 2008 21:01:43 GMT

Thanks guys,

All your replies were very helpful indeed.