Tao Zhu

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in fav of https://github.com/solana-labs/solana/pull/34865, and bunch of test hardening PRs before it.

agree this is better approach.

> 2\. we need to make sure we are **always** grabbing these locks in a "safe" order so that we cannot dead-lock (i.e. don't allow thread 1 to take cost_tracker...

Been back-n-forth on several tries, I found I largely agree with @apfitzge points above. To not to grab two locks at a time, and do it in batch instead of...

> > Yeah taking both locks is probably too risky.. How about we first reserve as much as cost as we need in qos and then keep track of how...

> So it seems in either case we want to have the order: (lock, qos reserve, unlock) Yea, I initially considered this (without thinking about new scheduler behavior). I felt...

> https://github.com/solana-labs/solana/pull/34865/files#diff-ed47b4a0198313377e091bb3957bbbc63d937805426d1b2b6de39d0a50d32a0cR6673 > > I think getting it off the fee generator was incorrect here. Seems like the right way would probably be to get it off of the blockhash...

> https://github.com/solana-labs/solana/pull/34865/files#diff-ed47b4a0198313377e091bb3957bbbc63d937805426d1b2b6de39d0a50d32a0cR6673 perhaps due to testnet genesis sets `target_lamports_per_signature: 0`, so the fee_structure derived form it would have 0 lamports-per-signature. Going to modify it to see if makes difference...

A bug is introduced [here](https://github.com/solana-labs/solana/pull/34865/files#diff-dc3100b413f7846958dc91a974f3ee159f5e20f191defc4160eb96fe43fe8d45L125-R123): when the `lamports_per_signature` param is zero, it used to wipe out entire fee to zero; the PR made it only sets signature_fee to zero, priority...