[Kst] kst 2.x: dbus interface / datasource API

[Barth Netterfield]

On Monday 08 March 2010 16:17:34 nicolas.brisset at free.fr wrote:
> Speaking of that, I was also wondering whether it would not be
> time to look into getdata. We will certainly investigate a bit in that
> area, though we were wondering how it performs if there are many variables
> to be written so often into so many files. File IO has the reputation of
> being slow. Is there some sort of buffering/memory caching being done? 

That is sort up up to the program doing the writing.  Our writer is in a 
different thread than the DAC reader, and the writes are buffered so the 
writer can keep up.  If you wrote them one at a time, you would be in trouble.

> Is
> there a limit on the number of variables that can be recorded
> simultaneously? 

Not really.

> We routinely have simulations producing a few thousand
> vars at 50 Hz... 

Our common case as about 1000 channels, most at 100Hz, so... similar to you.  
We have no problem on old hardware.

> Maybe in such a case netCDF or CDF are better choices?

getdata is optimized for efficient reading, at the expense of less efficient 
writing - so each field is stored in a separate file on disk.