4a6dec7193
The latest idle conns fix 9481cef948 ("BUG/MEDIUM: connection: do not
reinsert a purgeable conn in idle list") addresses a very hard-to-hit
case which manifests itself with an attempt to reuse a connection fails
because conn->mux is NULL:
Program terminated with signal SIGSEGV, Segmentation fault.
#0 0x0000655410b8642c in conn_backend_get (reuse_mode=4, srv=srv@entry=0x6554378a7140,
sess=sess@entry=0x7cfe140948a0, is_safe=is_safe@entry=0,
hash=hash@entry=910818338996668161) at src/backend.c:1390
1390 if (conn->mux->takeover && conn->mux->takeover(conn, i, 0) == 0) {
However the condition that leads to this situation can be detected
earlier, by the presence of the connection in the toremove_list, whose
race window is much larger and easier to detect.
This patch adds a few BUG_ON_STRESS() at selected places that an detect
this condition. When built with -DDEBUG_STRESS and run under stress with
two distinct processes communicating over H2 over SSL, under a stress of
400-500k req/s, the front process usually crashes in the first 10-30s
triggering in _srv_add_idle() if the fix above is reverted (and it does
not crash with the fix).
This is mainly included to serve as an illustration of how to instrument
the code for seamless stress testing.
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.