Parity-Ethereum 2.2.2-beta is an exciting release. Among others, it improves sync performance, peering stability, block propagation, and transaction propagation times. Also, a warp-sync no longer removes existing blocks from the database, but rather reuses locally available information to decrease sync times and reduces required bandwidth.
Before upgrading to 2.2.2, please also verify the validity of your chain specs. Parity Ethereum now denies unknown fields in the specification. To do this, use the chainspec tool:
```
cargo build --release -p chainspec
./target/release/chainspec /path/to/spec.json
```
Last but not least, JSONRPC APIs which are not yet accepted as an EIP in the `eth`, `personal`, or `web3` namespace, are now considere experimental as their final specification might change in future. These APIs have to be manually enabled by explicitly running `--jsonrpc-experimental`.
The full list of included changes:
- Backports For beta 2.2.2 ([#9976](https://github.com/paritytech/parity-ethereum/pull/9976))
- Version: bump beta to 2.2.2
- Add experimental RPCs flag ([#9928](https://github.com/paritytech/parity-ethereum/pull/9928))
- Keep existing blocks when restoring a Snapshot ([#8643](https://github.com/paritytech/parity-ethereum/pull/8643))
- Rename db_restore => client
- First step: make it compile!
- Second step: working implementation!
- Refactoring
- Fix tests
- Migrate ancient blocks interacting backward
- Early return in block migration if snapshot is aborted
- Remove RwLock getter (PR Grumble I)
- Remove dependency on `Client`: only used Traits
- Add test for recovering aborted snapshot recovery
- Add test for migrating old blocks
- Release RwLock earlier
- Revert Cargo.lock
- Update _update ancient block_ logic: set local in `commit`
- Update typo in ethcore/src/snapshot/service.rs
- Adjust requests costs for light client ([#9925](https://github.com/paritytech/parity-ethereum/pull/9925))
- Pip Table Cost relative to average peers instead of max peers
- Add tracing in PIP new_cost_table
- Update stat peer_count
- Use number of leeching peers for Light serve costs
- Prevent zero network ID ([#9763](https://github.com/paritytech/parity-ethereum/pull/9763)) and drop support for Olympic testnet ([#9801](https://github.com/paritytech/parity-ethereum/pull/9801)): The Olympic test net is dead for years and never used a chain ID but network ID zero. Parity Ethereum is now preventing the network ID to be zero, thus Olympic support is dropped. Make sure to chose positive non-zero network IDs in future.
- Multithreaded snapshot creation ([#9239](https://github.com/paritytech/parity-ethereum/pull/9239)): adds a CLI argument `--snapshot-threads` which specifies the number of threads. This helps improving the performance of full nodes that wish to provide warp-snapshots for the network. The gain in performance comes with a slight drawback in increased snapshot size.
- Expose config max-round-blocks-to-import ([#9439](https://github.com/paritytech/parity-ethereum/pull/9439)): Parity Ethereum imports blocks in rounds. If at the end of any round, the queue is not empty, we consider it to be _importing_ and won't notify pubsub. On large re-orgs (10+ blocks), this is possible. The default `max_round_blocks_to_import` is increased to 12 and configurable via the `--max-round-blocks-to-import` CLI flag. With unstable network conditions, it is advised to increase the number. This shouldn't have any noticeable performance impact unless the number is set to really large.
- Increase Gas-floor-target and Gas Cap ([#9564](https://github.com/paritytech/parity-ethereum/pull/9564)): the default values for gas floor target are `8_000_000` and gas cap `10_000_000`, similar to Geth 1.8.15+.
- Produce portable binaries ([#9725](https://github.com/paritytech/parity-ethereum/pull/9725)): we now produce portable binaries, but it may incur some performance degradation. For ultimate performance it's now better to compile Parity Ethereum from source with `PORTABLE=OFF` environment variable.
- RPC: `parity_allTransactionHashes` ([#9745](https://github.com/paritytech/parity-ethereum/pull/9745)): Get all pending transactions from the queue with the high performant `parity_allTransactionHashes` RPC method.
- Support `eth_chainId` RPC method ([#9783](https://github.com/paritytech/parity-ethereum/pull/9783)): implements EIP-695 to get the chainID via RPC.
- AuRa: finalize blocks ([#9692](https://github.com/paritytech/parity-ethereum/pull/9692)): The AuRa engine was updated to emit ancestry actions to finalize blocks. The full client stores block finality in the database, the engine builds finality from an ancestry of `ExtendedHeader`; `is_epoch_end` was updated to take a vec of recently finalized headers; `is_epoch_end_light` was added which maintains the previous interface and is used by the light client since the client itself doesn't track finality.
- Light-fetch: Differentiate between out-of-gas/manual throw and use required gas from response on failure ([#9824](https://github.com/paritytech/parity-ethereum/pull/9824))
- Drops support for olympic testnet, closes [#9800](https://github.com/paritytech/parity-ethereum/issues/9800) ([#9801](https://github.com/paritytech/parity-ethereum/pull/9801))
- Replace `tokio_core` with `tokio` (`ring` -> 0.13) ([#9657](https://github.com/paritytech/parity-ethereum/pull/9657))
- Support eth_chainId RPC method ([#9783](https://github.com/paritytech/parity-ethereum/pull/9783))
- Verify block syncing responses against requests ([#9670](https://github.com/paritytech/parity-ethereum/pull/9670))
- Add a new RPC `parity_submitWorkDetail` similar `eth_submitWork` but return block hash ([#9404](https://github.com/paritytech/parity-ethereum/pull/9404))
- Resumable EVM and heap-allocated callstack ([#9360](https://github.com/paritytech/parity-ethereum/pull/9360))
- Hardfork the testnets ([#9562](https://github.com/paritytech/parity-ethereum/pull/9562))
- Calculate sha3 instead of sha256 for push-release. ([#9673](https://github.com/paritytech/parity-ethereum/pull/9673))
- Ethcore-io retries failed work steal ([#9651](https://github.com/paritytech/parity-ethereum/pull/9651))
- Fix(light_fetch): avoid race with BlockNumber::Latest ([#9665](https://github.com/paritytech/parity-ethereum/pull/9665))
- Test fix for windows cache name... ([#9658](https://github.com/paritytech/parity-ethereum/pull/9658))
- Refactor(fetch) : light use only one `DNS` thread ([#9647](https://github.com/paritytech/parity-ethereum/pull/9647))
- Ethereum libfuzzer integration small change ([#9547](https://github.com/paritytech/parity-ethereum/pull/9547))
- Cli: remove reference to --no-ui in --unlock flag help ([#9616](https://github.com/paritytech/parity-ethereum/pull/9616))
- Remove master from releasable branches ([#9655](https://github.com/paritytech/parity-ethereum/pull/9655))
- Ethcore/VerificationQueue don't spawn up extra `worker-threads` when explictly specified not to ([#9620](https://github.com/paritytech/parity-ethereum/pull/9620))
- New ethabi ([#9511](https://github.com/paritytech/parity-ethereum/pull/9511))
- Remove initial token for WS. ([#9545](https://github.com/paritytech/parity-ethereum/pull/9545))
- Net_version caches network_id to avoid redundant aquire of sync readlock ([#9544](https://github.com/paritytech/parity-ethereum/pull/9544))
- Correct before_script for nightly build versions ([#9543](https://github.com/paritytech/parity-ethereum/pull/9543))
- Deps: bump kvdb-rocksdb to 0.1.4 ([#9539](https://github.com/paritytech/parity-ethereum/pull/9539))
- State: test when contract creation fails, old storage values should re-appear ([#9532](https://github.com/paritytech/parity-ethereum/pull/9532))
- Allow dropping light client RPC query with no results ([#9318](https://github.com/paritytech/parity-ethereum/pull/9318))
- Bump master to 2.2.0 ([#9517](https://github.com/paritytech/parity-ethereum/pull/9517))
- Enable all Constantinople hard fork changes in constantinople_test.json ([#9505](https://github.com/paritytech/parity-ethereum/pull/9505))
- [Light] Validate `account balance` before importing transactions ([#9417](https://github.com/paritytech/parity-ethereum/pull/9417))
- In create memory calculation is the same for create2 because the additional parameter was popped before. ([#9522](https://github.com/paritytech/parity-ethereum/pull/9522))
- Update patricia trie to 0.2.2 ([#9525](https://github.com/paritytech/parity-ethereum/pull/9525))
- Replace hardcoded JSON with serde json! macro ([#9489](https://github.com/paritytech/parity-ethereum/pull/9489))
- Fix typo in version string ([#9516](https://github.com/paritytech/parity-ethereum/pull/9516))
