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title: EPF6 Dev Updates – Week 3

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# EPF6 Dev Updates – Week 3

As, even after going through major backfill code, I was not very clear about the scope for work as epf project, the lodestar team is expecting, so I decided to reach out lodestar team on chainsafe discord.
I got to know that the current backfill implementation was disabled due to performance and code quality issues. So, I need to work on a new implementation from scratch starting with the first priciples. The main focus is on designing an efficient algorithm and then development.

They also suggested to look into implementations from other clients:
https://github.com/Consensys/teku/blob/4fbce93cb5ad0817ed1e46d4cc9dbcb1915c7a7d/ethereum/statetransition/src/main/java/tech/pegasys/teku/statetransition/datacolumns/CustodyGroupCountManagerImpl.java#L140

Further, I went through https://github.com/Consensys/teku/blob/800d48bd6eed46c94de8308d13f6084a69ffaca4/beacon/pow/src/main/java/tech/pegasys/teku/beacon/pow/Eth1BlockFetcher.java
This seems like outdated implementation(last changed 5yrs ago) of backfill. There are APIs for fetching historical data but they seem more like fetching specific blocks on requirement.
I've decided first to write some basic algorithm for backfilling blocks and iteratively fix it. Then, I'll take up the case of blobs, till then I'll explore more of peerDAS code and try to understand it more.

As there was also discussion that we will be utilising worker threads for backfilling, as it should not block the main thread and cause issues like before. So, I started exploring more about it.
It seemed fascinating, as this was the first time I actually realized the limitations of languages such as javascript.
I explored how lodestar implements worker threads using [@chainsafe/threads](https://github.com/ChainSafe/threads.js). Did some experiments with it (https://threads.js.org/usage) and async nature of js.
Some refs:
 Got little lost into javascript and it's execution technicalities.
Then, came back to working on drafting a proposal.
WIP.



Week 4 goals:
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- Some important things still due:
[Lodestar | Technical Walkthrough](https://www.youtube.com/watch?v=wqQDomhpZeQ)
Lighouse implementation deep dive
- Complete the proposal and present in [epf office hours](https://github.com/eth-protocol-fellows/cohort-six/issues/113)
- Write basic initial algorithm & get feedback
- explore peerDAS (https://eips.ethereum.org/EIPS/eip-7594) & its specs(https://github.com/ethereum/consensus-specs/tree/9d377fd53d029536e57cfda1a4d2c700c59f86bf/specs/fulu/)