Possibility to have multiple writers

[tmadlener]

It would be nice to have the possibility to have multiple writers in one algorithm chain. This would make it possible to create e.g. a "debug level" output file and a standard output file. Or further in the future the possibility to run a reco + analysis chain and keep both levels.

Is it already possible now to have multiple Writers? (Including the necessity to sequence it properly)

[jmcarcell]

This is certainly not supported right now since it is assumed there is only one Writer. I have a prototype for supporting multiple writers since this has been mentioned a few times already. I think another improvement that (I think) @Zehvogel has mentioned is to be able to insert the writer wherever one wants in the chain so that one can start checking the output without even having to wait for the first event to finish (useful if the whole chain takes a long time). Any thoughts on that? That may require more changes since currently we just run sequentially the writer at the end, guaranteeing that all the collections are there, since the Writer doesn't take the collections in its input and thus is not scheduled after the algorithms whose collections it has to write.

[tmadlener]

insert the writer wherever one wants in the chain so that one can start checking the output without even having to wait for the first event to finish (useful if the whole chain takes a long time). Any thoughts on that?

Yes, that would be crucial to make it really useful, I think.