Parallel processing issues

First of all, I dont know if the problem I am having is suitable for this forum group as I cannot find a better forum group to posted on.
I have written a program which it has a web part and a backend part. As soon as the program is deployed onto and oc4j, it will starts retrieving data from the database and perform it task at the backend part. The web will allow me to check on some basic info about application and retrieve log from the log directory.
As long as I deployed onto a single non-clustered server with only 1 oc4j instance, I am all good, but whenever I have a clustered server environment consists of 4 hosts with the following configurations, I am toasted.
     Each host will have its own oc4j instance with a copy of the program deployed onto.
     2 of the 4 oc4j will be turn on immediately and the other 2 oc4j will serves as backup. Whenever the 2 active oc4j shuts down, the backup oc4j will become active and take over the job.
     The 2 active oc4j will be running the program in parallel for sharing the work load.
The problem arises when the 2 active copies of the program are running in parallel. Since the program will retrieve a transaction id from the db, and then perform some necessary action and save a new id number that is larger than the retrieved id back to the db. These actions from the program will be performed repeatedly with 1 minute time interval between them. If 2 copies of the program are running in different oc4j instance in parallel, then there is a chance that both copies of the program will retrieve the same transaction id at the beginning which this should be strictly forbidden due to some business logic issues.
So my question is this, how should the program be designed so the 2 copies of the program reside on 2 different oc4j can have some mutual agreement and knowing that they are working on some duplicate transaction id. I will need to have an exact copy of the program deployed onto each oc4j instances.

Hello,
you need to lock the database record which contains the session id you are working on. Use a select for update statement. If one application has a lock on the record, than the second one will wait until the lock is released (the transaction is commited or rolled back) before his select for update statement will return the record. Or you can specify to skip the locked records, so the second application won't get blocked. Anyway only one application will be able to read the record in question.
You can see examples here:
[http://www.techonthenet.com/oracle/cursors/for_update.php]
Zsom

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hi,
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Hello Venkata,
You can achieve parallel processing by using CALL FUNCTION .... STARTING NEW TASK <task name>.
In this case function module runs in asynchronous mode without stopping calling program.
For more details you can refer following link:
https://wiki.sdn.sap.com/wiki/display/Snippets/Easilyimplementparallelprocessinginonlineandbatchprocessing
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Hi Kunal,
Check this links:
https://www.sdn.sap.com/irj/sdn/go/portal/prtroot/docs/library/uuid/b06c3f96-ed4f-2a10-1693-f2c76a39988f
https://www.sdn.sap.com/irj/sdn/go/portal/prtroot/docs/library/uuid/90886731-21e4-2a10-2ebf-901c2c2b4e3d
Basically, what you do is:
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Transaction for creating APD is RSANWB. It's pretty easy and it's a graphical interface, so you should find your way easily.
Hope this helps.
Regards,
Diego

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Hi,
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Hi,
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Hi Henrique,
they would not necessarily start at the same time but shouldnt also be queued - Customer expecting the response within a 17 sec or 20 Sec but coming response 34 sec will not ok for the customer..tomorrow need add some more target again 17 sec will take...How PI can handle the Multi threading they are checking...I am not sure this problem fixed in PI 7.1 or not.
there're # of connection restrictions in your system? Check that - Where can I check connections restrictions...If you know pls through some light on this.
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Hi experts,
I am using BAPI_PO_CRATE1 in parallel processing to create multiple Purchase Orders. The Programs is creating only one PO (the Ist one) however it should create multiple PO as per the program and data.
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Points are sure.
Thanks & Regards.
Anirudh

Without looking at some poriton of the code around this call and your parallel processing logic, it will be difficult to say.

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Dear Oracle Experts,
I would like to use the Parallel Processing feature on My production database running on Unix Box.
No: of CPU in each node is 8 and its RAC database
Before going for this option i would like to certain things regarding Parallel Processing.
1. According to my server specification how much DOP i can specify.
2. Which option for Setting Parallel is good
a. Using the 'alter table A parallel 4' or passing the parallel hints in the sql statements
3. We have a batch processing jobs which are loading data into the tables from flat files (24*7) using sql loader. is it possible to parallel this operation and any negative effect if enabled parallel.
4. Query or DML - which one will be perform best with parallel option.
5. What are the negative issue if parallel option is enabled.
6. what are the things to be taken care while enabling the parallel option.
Thanks in Advance
Edited by: user585870 on Jun 7, 2009 12:04 PM

Hi,
first of all, you should read [Using Parallel Execution|http://download.oracle.com/docs/cd/B19306_01/server.102/b14223/usingpe.htm#DWHSG024] in documentation for your version - almost all of these topics are covered there.
1. According to my server specification how much DOP i can specify.It depends not only on number of CPU. More important factors are settings of PARALLEL_MAX_SERVERS and PARALLEL_ADAPTIVE_MULTI_USER.
2. Which option for Setting Parallel is good - Using the 'alter table A parallel 4' or passing the parallel hints in the sql statementsIt depends on your application. When setting PARALLEL on a table, all SQL dealing with that table would be considered for parallel execution. So if it is normal for your app to use parallel access to that table, it's OK. If you want to use PX on a limited set of SQL, then hints or session settings are more appropriate.
3. We have a batch processing jobs which are loading data into the tables from flat files (24*7) using sql loader. is it possible to parallel this operation and any negative effect if enabled parallel.Yes, refer to documentation.
4. Query or DML - which one will be perform best with parallel option.Both may take advantages of using PX (with some restrictions to Parallel DML) and both may run slower than non-PX versions.
5. What are the negative issue if parallel option is enabled.1) Object checkpoint happens before starting parallel FTS (true for >=10gR2, before that version tablespace checkpoint was used)
2) More CPU and memory resources are used with PX - it may be both benefit and an issue, especially with concurrent PX.
6. what are the things to be taken care while enabling the parallel option.Read the documentation - it contains almost all you need to know. Since you are using RAC, you sould not forget about method of PX slaves load balancing between nodes. If you are on 10g, refer to INSTANSE_GROUPS/PARALLEL_INSTANCE_GROUPS parameters, if you are using 11g then properly configure services.

Parallel processing using ABAP objects

Hello friends,
                    I had posted in the performance tuning forum , regarding a performance issue problem , I am reposting it as it involves OO concept .
the link for the previous posting
Link: [Independent processing of elements inside internal table;
Here is the scenario,
I have a internal table with 10 records(indepentent) , and i need to process them .The processing of one record doesnt have any influence on the another . When we go for loop , the performance issue is that , the 10 th record has to wait until the 9 records get processed even though there is no dependency on the output.
Could some one tell a way out to improve the performance..
If i am not clear with the question , i would explain it still clearer...
A internal table has 5 numbers , say( 1,3,4,6,7)
we are trying to find square of each number ,,,
If it is a loop the finding of suare of 7 has to wait until 6 is getting completed and it is waste of time ...
This is related to parallel processing , I have refered to parallel processing documents,But I want to do this conceptually ..
I am not using conventional procedural paradigm but Object orientedness...I am having a method which is performing this action .What am I supposed to do in that regard.
Comradely ,
K.Sibi

Hi,
As examplified by Edward, there is no RFC/asynchronous support for Methods of ABAP Objects as such. You would indeed need to "wrap" your method or ABAP Object in a Function Module, that you can then call with the addition "STARTING NEW TASK". Optionally, you can define a Method that will process the results of the Function Module that is executed asynchronously, as demonstrated as well in Edward's program.
You do need some additional code to avoid the situation where your program takes all the available resources on the Application Server. Theoretically, you cannot bring the server or system down, as there is a system profile parameter that determines the maximum number of asynchronous tasks that the system will allow. However, in a productive environment, it would be a good idea to limit the number of asynchronous tasks started from your program so that other programs can use some as well.
Function Group SPBT contains a set of Function Modules to manage parallel processing. In particular, FM SPBT_INITIALIZE will "initialize" a Server Group and return the maximum number of Parallel Tasks, as well as the number of free ones at the time of the initialization. The other FM of interest is SPBT_GET_CURR_RESOURCE_INFO, that can be called after the Server Group has been initialized, whenever you want to "fork" a new asynchronous task. This FM will give you the number of free tasks available for Parallel Processing at the time of calling the Function Module.
Below is a code snippet showing how these Function Modules could be used, so that your program always leaves a minimum of 2 tasks for Parallel Processing, that will be available for other programs in the system.
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              currently_no_resources_avail         = 4
              no_pbt_resources_found               = 5
              cant_init_different_pbt_groups       = 6
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You may also need to program a WAIT statement, to wait until all asynchronous tasks "forked" from your program have completed their processing. Otherwise, you might find yourself in the situation where your main program has finished its processing, but some of the asynchronous tasks that it started are still running. If you do not need to report on the results of these asynchronous tasks, then that is not an issue. But, if you need to report on the success/failure of the processing performed by the asynchronous tasks, you would most likely report incomplete results in your program.
In the example where you have 10 entries to process asynchronously in an internal table, if you do not WAIT until all asynchronous tasks have completed, your program might report success/failure for only 8 of the 10 entries, because your program has completed before the asynchronous tasks for entries 9 and 10 in your internal table.
Given the complexity of Parallel Processing, you would only consider it in a customer program for situations where you have many (ie, thousands, if not tens of thousands) records to process, that the processing for each record tends to take a long time (like creating a Sales Order or Material via BAPI calls), and that you have a limited time window to process all of these records.
Well, whatever your decision is, good luck.

Error while using RSDRI_INFOPROV_READ : parallel processing error

Hi
I am also facing parallel processing error while using the function module RSDRI_INFOPROV_READ in transformation.
when only one data package is there, the load happens without any issue. But when multiple data packages are involved the load fails with an error "Exception in parallel processing".

Hi Lijo,
I got the following information from the function module documentation of the FM RSDRI_INFOPROV_READ.
If neither I_SAVE_IN_FILE nor I_SAVE_IN_TABLE are set, then the return takes place in the form of packages (that is an internal table), of value I_PACKAGESIZE. A negative value means that the return should be in one package.
Prathish.

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As per SAP Note 1230721 - Java Proxy Generation - Support for Parallel Processing, when we generate a java proxy from an interface we are supposed to get 2 archives (one for serial processing and another suffixed with "PARALLEL" for parallel processing of jaav proxies in JPR).
https://websmp230.sap-ag.de/sap(bD1lbiZjPTAwMQ==)/bc/bsp/spn/sapnotes/index2.htm?numm=1230721
We are on the correct patch level as per the Note, however when we generate java proxy from the IR for an outbound interface, it genrates only 1 zip archive (whose name we ourselves provide in the craete new archive section). This does not enable the parallel processsing of the messages in JPR.
Could you please help me in this issue, and guide as to how archives can be generated for parallel processing.
Thanks & Regards,
Rosie Sasidharan.

Hi,
Thanks a lot for your reply, Prateek.
I have already checked SAP Note 1142580 - "Java Proxy is not processing messages in parallel" where they ask to modify the ejb-jar.xml. However, on performing the change in ejb-jar.xml and while building the EAR, I get the following error:
Error! The state of the source cache is INCONSISTENT for at least one of the request DCs. The build might produce incorrect results.
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Kindly help me if any of you have worked on such a scenario.
Thanks in advance,
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Rosie Sasidharan.

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I am facing issue with Exclusive Gateway in Parallel Process.
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Hi Unni,
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Hello,
I am trying since 2 days to solve the issue of parallel process in background without using FPP.
For which I want to call function module of class method in new task but to be processed by background process and not dialog.
I searched so many websites but everyone has suggesteed to 'call function in background task' . But the fact is the processing of function happens by dailog process even in this case.
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Balaji,
Is the name of the button between single or double quotes?
Regards,
Dan
Blog: http://DanielMcGhan.us/
Work: http://SkillBuilders.com/

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