On 16-Feb-2015 08:56 -0600, Jevgeni Astanovski wrote:

Does anyone have any idea why C++ program is significantly slower than
C program?

Explain the situation.
I have a number of APIs that are called via RPC, access some tables,
make some calculations and return some structures to the caller.
They've all been written on ILE/C.
Recently I started to experiment with porting them to ILE/C++.

What I saw is that time increase looks like it has a proportional
nature. I tested API in 3 cases (number of tests is over 100):
simple request, medium request; complicated request

and the timing is:
• Simple C: 1ms; Simple C++ : 2ms
• Medium C: 3ms; Simple C++ : 7ms
• Long C: 25ms; Long C++: 60ms.

The difference is in number of records read from table and a number
of calculations. That is, a
• simple one retrieves less that 10 records;
• medium - more than 10 and
• long - more than 100. Program makes a lot of calculations
with packed decimal.

Any idea why it is like that

Followups determined the issue is apparently for the calculations using the Packed BCD numeric data type using the C++ libraries.

and is there anything that can be done about it?

With so few specifics of the scenario, the following may be way off the mark, but as a possibility:

Perhaps the /calculations with packed decimal/ over data that is apparently /record data/ of /some tables/ could be performed by the SQL?

This thread ...


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