58d7eb0f2c
ThreadNotifyWallets was created in order to decouple wallet scanning of transactions from the main chain updates, avoiding timing leaks to network peers. To further ensure that not even lock contention could be used to extract timing information, ThreadNotifyWallets collects update information from the main chain on integer second boundaries. In general this means that the wallet is processing the last second's worth of blocks between each synchronization point. However, when there are sequences of blocks that are costly for the wallet to scan, it may take the wallet longer than a second to process a second's worth of blocks connected to the main chain. This means that ThreadNotifyWallets needs to wait until the next integer second boundary before collecting the next set of updates, which means it will be processing at least two seconds' worth of blocks. For extended periods where the chain contains many outputs, the wallet will get progressively further behind the main chain. At the time that ThreadNotifyWallets was created, the above behaviour was fine, because while the wallet scanning process consumed a lot of CPU time, it did not consume much memory (as blocks are stored on disk). However, we recently added batch scanning, which requires allocating memory for each output that is being scanned. For a wallet with a growing gap between its scanned-to height and the chain tip height, the size of the necessary allocation will grow with each integer second boundary crossed, until the node reaches OOM. The solution is to implement backpressure: if we reach a memory limit before we've finished adding blocks to the batch scanners, then we start consuming the results from the batch scanner to free up memory space for subsequent batches. This commit implements the logic necessary to interleave batch creation and batch result consumption. It does not apply any batch memory limits, and as such should be effectively a no-op refactor. Co-authored-by: Daira Hopwood <daira@jacaranda.org> |
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README.md
Zcash 5.2.0
What is Zcash?
Zcash is an implementation of the "Zerocash" protocol. Initially based on Bitcoin's design, Zcash intends to offer a far higher standard of privacy through a sophisticated zero-knowledge proving scheme that preserves confidentiality of transaction metadata. More technical details are available in our Protocol Specification.
The zcashd Full Node
This repository hosts the zcashd software, a Zcash consensus node
implementation. It downloads and stores the entire history of Zcash
transactions. Depending on the speed of your computer and network
connection, the synchronization process could take several days.
The zcashd code is derived from a source fork of
Bitcoin Core. The code was forked
initially from Bitcoin Core v0.11.2, and the two codebases have diverged
substantially.
🔒 Security Warnings
See important security warnings on the Security Information page.
Zcash is experimental and a work in progress. Use it at your own risk.
📒 Deprecation Policy
This release is considered deprecated 16 weeks after the release day. There is an automatic deprecation shutdown feature which will halt the node some time after this 16-week period. The automatic feature is based on block height.
Other Zcash Implementations
The Zebra project offers a different Zcash consensus node implementation, written largely from the ground up.
Getting Started
Please see our user guide for instructions on joining the main Zcash network.
Need Help?
- 📘 See the documentation at the ReadTheDocs for help and more information.
- 📨 Ask for help on the Zcash forum.
- 💬 Join our community on Discord
Participation in the Zcash project is subject to a Code of Conduct.
Building
Build Zcash along with most dependencies from source by running the following command:
./zcutil/build.sh -j$(nproc)
Currently, Zcash is only officially supported on Debian and Ubuntu. See the Debian / Ubuntu build for detailed instructions.
License
For license information see the file COPYING.