Re: TTree::AutoSave

From: Volker Boerchers (boercher@physik.uni-bremen.de)
Date: Mon Nov 01 1999 - 09:38:45 MET


> The TTree::AutoSave function saves the Tree header in memory including:
>   - the branches/leaves data structure
>   - the branch buffers in memory
> 
> Depending the number of branches in your tree and the branch buffer size
> the space occupied by the Tree header may be non negligible. It must be
> bigger than the size of one single event. It does not make sense to call
> this function after each Fill. The intented use is to save at regular
> intervals depending on;
>   - how much data has been written so far on disk
>   - how many cpu/rt seconds used since the last autosave

in our case the fill happens only once after each event (which takes a
lot of cpu time). So this is actually a good occasion for a save
(perhaps only after each n'th event).

> Currently AutoSave does not delete the Tree headers on disk generated
> by previous Autosave. If you have too many Autosave, you will get (what
> you found) many Tree headers and the space can be much bigger than the
> useful
> data.
> I could implement an automatic delete of the previous AutoSave once
> the current Autosave has successfully completed.

This would be a great improvement IMHO because older AutoSave data
is of no use, right?
In the meanwhile, can I do the deletion `by hand'? (I can't, I suppose...)

Regards,
  Volker

::.::::.::::.::::.::::.::::.::::.::::.::::.::::.::::.::::.::::.::::.::
Volker B"orchers, Uni Bremen, NW1, Raum 03160, Tel. +49-421-218-4522
 mailto:boercher@physik.uni-bremen.de
 http://hix.physik.uni-bremen.de/~boercher



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