In commit 3372a2ea00 ("BUG/MEDIUM: queues: Stricly respect maxconn for outgoing connections"), it has been ensured that srv->served is held as long as possible around the periods where a stream is attached to a server. However, it's decremented early when entering sess_change_server, and actually just before detaching from that server's list. While there is theoretically nothing wrong with this, it prevents us from looking at this counter to know if streams are still using a server or not. We could imagine decrementing it much later but that wouldn't work with leastconn, since that algo needs ->served to be final before calling lbprm.server_drop_conn(). Thus what we're doing here is to detach from the server, then decrement ->served, and only then call the LB callback to update the server's position in the tree. At this moment the stream doesn't know the server anymore anyway (except via this function's local variable) so it's safe to consider that no stream knows the server once the variable reaches zero.
HAProxy
HAProxy is a free, very fast and reliable reverse-proxy offering high availability, load balancing, and proxying for TCP and HTTP-based applications.
Installation
The INSTALL file describes how to build HAProxy. A list of packages is also available on the wiki.
Getting help
The discourse and the mailing-list are available for questions or configuration assistance. You can also use the slack or IRC channel. Please don't use the issue tracker for these.
The issue tracker is only for bug reports or feature requests.
Documentation
The HAProxy documentation has been split into a number of different files for ease of use. It is available in text format as well as HTML. The wiki is also meant to replace the old architecture guide.
Please refer to the following files depending on what you're looking for:
- INSTALL for instructions on how to build and install HAProxy
- BRANCHES to understand the project's life cycle and what version to use
- LICENSE for the project's license
- CONTRIBUTING for the process to follow to submit contributions
The more detailed documentation is located into the doc/ directory:
- doc/intro.txt for a quick introduction on HAProxy
- doc/configuration.txt for the configuration's reference manual
- doc/lua.txt for the Lua's reference manual
- doc/SPOE.txt for how to use the SPOE engine
- doc/network-namespaces.txt for how to use network namespaces under Linux
- doc/management.txt for the management guide
- doc/regression-testing.txt for how to use the regression testing suite
- doc/peers.txt for the peers protocol reference
- doc/coding-style.txt for how to adopt HAProxy's coding style
- doc/internals for developer-specific documentation (not all up to date)
License
HAProxy is licensed under GPL 2 or any later version, the headers under LGPL 2.1. See the LICENSE file for a more detailed explanation.