DAL: Batch crypto verification to reduce computation time
What
Allow to initialize the gossipsub library in "batch mode" where application messages are stored for a time T and treated all in once once delay is over. Use this mechanism in the DAL node to batch received shards and trigger crypto verification every second with all recently received shards.
Why
Because verifying a batch of shards associated to the same commitment is less computer intensive than verifying shards one by one, since some computations can be done once for all.
Design doc
Manually testing the MR
One can launch a DAL node and check that it behaves as before (but faster).
Launched an experiment with tezt-cloud with 64 producers, one for each slot, 8 seconds block time (so with a bandwidth of 1MB/s) and c2-standard-4 machines (so quite powerful ones). The results I get is that even with 8 bakers having the same stake (so 12.5% each), the results are good (all published data are attested), whereas when I ran the same experiment in February, with 14 bakers (so 7.1% of the stake) not all slots were attested because bakers struggled with crypto.