32765aca5c
bd4b1524eainit: do not count file descriptors for HTTPServer if -server=0 (Matthew Zipkin)b08662060dinit: account for maximum file descriptors needed by HTTP (Matthew Zipkin)cc2acebefbhttp: configure simultaneous connection limit with -rpcmaxconnections (Matthew Zipkin)b3d6d2d1a7http: limit connected clients to 16 (Matthew Zipkin)86651d8197scripted-diff: Rename nUserBind, nBind, nMaxConnections to snake_case (Matthew Zipkin) Pull request description: Introduces a new configuration option `-rpcmaxconnections` with default value `16`. This is used to limit the number of simultaneous `HTTPClient` connected to the `HTTPServer`. When the limit is reached, new pending connections remain queued in the kernel's socket buffer. Those connections have complete TCP handshakes with the kernel but do not occupy any application memory. The previous libevent-based HTTP server had no limit on connections but it did have a limit on the kernel socket queue:e7ff4ef2b4/http.c (L3510)```c if (listen(fd, 128) == -1) { ``` The current HTTP server, like the p2p server, uses a platform constant here:b6becf3534/src/httpserver.cpp (L743)(on my macOS `SOMAXCONN` is `128` but on my Debian machine it's `4096`) The default of 16 was chosen as a reasonable upper bound for single-user RPC use cases. Systems designed to handle more simultaneous HTTP connections than this (previously relying on the absence of a limit) can adjust the setting. ## File descriptors Because of the connection limit, we can now account for the maximum number of file descriptors needed by the HTTP server. This addresses several issues (#11368 #11322 maybe #27732) that could have been fixed by a PR waiting in vain for a libevent release (#27731). ## Bonus performance improvement The new limit is managed in a loop that drains the kernel's socket queue with `accept()`. All pending connections from the queue (up to the limit) are processed in one single call to `SocketHandlerListening()`. The previous code would only accept one connection from the queue on each I/O loop tick, with a `SELECT_TIMEOUT` (50ms) sleep between each. ACKs for top commit: fjahr: tACKbd4b1524eajanb84: ACKbd4b1524eawinterrdog: tested ACKbd4b1524eahodlinator: Concept ACKbd4b1524eawillcl-ark: ACKbd4b1524eaTree-SHA512: 2ef7a96da4d7037c7343ec0ea03fda5bb55d10c2a071fce4929141297515923b203d3d338dbcb6599849768f52aa3c9da509fb5d1d6f7c574a1d2034ea2a9e74
Bitcoin Core integration/staging tree
For an immediately usable, binary version of the Bitcoin Core software, see https://bitcoincore.org/en/download/.
What is Bitcoin Core?
Bitcoin Core connects to the Bitcoin peer-to-peer network to download and fully validate blocks and transactions. It also includes a wallet and graphical user interface, which can be optionally built.
Further information about Bitcoin Core is available in the doc folder.
License
Bitcoin Core is released under the terms of the MIT license. See COPYING for more information or see https://opensource.org/license/MIT.
Development Process
The master branch is regularly built (see doc/build-*.md for instructions) and tested, but it is not guaranteed to be
completely stable. Tags are created
regularly from release branches to indicate new official, stable release versions of Bitcoin Core.
The https://github.com/bitcoin-core/gui repository is used exclusively for the development of the GUI. Its master branch is identical in all monotree repositories. Release branches and tags do not exist, so please do not fork that repository unless it is for development reasons.
The contribution workflow is described in CONTRIBUTING.md and useful hints for developers can be found in doc/developer-notes.md.
Testing
Testing and code review is the bottleneck for development; we get more pull requests than we can review and test on short notice. Please be patient and help out by testing other people's pull requests, and remember this is a security-critical project where any mistake might cost people lots of money.
Automated Testing
Developers are strongly encouraged to write unit tests for new code, and to
submit new unit tests for old code. Unit tests can be compiled and run
(assuming they weren't disabled during the generation of the build system) with: ctest. Further details on running
and extending unit tests can be found in /src/test/README.md.
There are also regression and integration tests, written
in Python.
These tests can be run (if the test dependencies are installed) with: build/test/functional/test_runner.py
(assuming build is your build directory).
The CI (Continuous Integration) systems make sure that every pull request is tested on Windows, Linux, and macOS. The CI must pass on all commits before merge to avoid unrelated CI failures on new pull requests.
Manual Quality Assurance (QA) Testing
Changes should be tested by somebody other than the developer who wrote the code. This is especially important for large or high-risk changes. It is useful to add a test plan to the pull request description if testing the changes is not straightforward.
Translations
Changes to translations as well as new translations can be submitted to Bitcoin Core's Transifex page.
Translations are periodically pulled from Transifex and merged into the git repository. See the translation process for details on how this works.
Important: We do not accept translation changes as GitHub pull requests because the next pull from Transifex would automatically overwrite them again.