Re: A C++ API for the pcas

[hill@luke.atdiv.lanl.gov (Jeff Hill)]

Re: C++ performance, employment, and porting issues.

> 
> I would like to raise the question of PERFORMANCE if core code is written
> in C++.  While I have no direct experience with C++ performance, I had a
> couple of recent conversations with experienced people that make me worry.
> 

I have compiled the existing pure ANSI C server library using C++ and this 
caused no significant change in performance. As with C, C++ programmers who 
care about performance will need know what it is that the compiler is doing 
for them so that they will know when it is inappropriate to use a particular
feature of the language. Issues related to memory management are likely
to have an impact on performance in a communications application such
as channel access.

> In my experience of applying for jobs with companies 
> in the UK, it does not seem to be very widely used.

In the states we see increasing demand for experienced C++ programmers.

> I always thought this was linked to the problem of producing
> portable C++ code.

This is a significant problem. In my opinion there are many dark passages 
in this language (C isnt immune here either). It is difficult to create an
ANSI standard for a moving target. 

Jeff

All elapsed times below are in fractions of a second.

% catime fred
search test
Elapsed Per Item = 0.001305
channel name=fred, native type=2, native count=1
        pend event test
Elapsed Per Item = 0.000170
float test
        async put test
Elapsed Per Item = 0.000048
        async get test
Elapsed Per Item = 0.000084
        synch get test
Elapsed Per Item = 0.003738
string test
        async put test
Elapsed Per Item = 0.000152
        async get test
Elapsed Per Item = 0.000174
        synch get test
Elapsed Per Item = 0.003986
integer test
        async put test
Elapsed Per Item = 0.000043
        async get test
Elapsed Per Item = 0.000079
        synch get test
Elapsed Per Item = 0.003674
free test
Elapsed Per Item = 0.000015

______________________________________________________________________
Jeffrey O. Hill			Internet	johill@lanl.gov
LANL MS H820			Voice		505 665 1831
Los Alamos, NM 87545 USA 	FAX		505 665 5107