The "show threads" command introduced early in the 2.0 dev cycle uses
appctx->st1 to store its context (the number of the next thread to dump).
It goes back to an era where contexts were shared between the various
applets and the CLI's command handlers.
In fact it was already not good by then because st1 could possibly have
APPCTX_CLI_ST1_PAYLOAD (2) in it, that would make the dmup start at
thread 2, though it was extremely unlikely.
When contexts were finally cleaned up and moved to their own storage,
this one was overlooked, maybe due to using st1 instead of st2 like
most others. So it continues to rely on st1, and more recently some
new flags were appended, one of which is APPCTX_CLI_ST1_LASTCMD (16)
and is always there. This results in "show threads" to believe it must
start do dump from thread 16, and if this thread is not present, it can
simply crash the process. A tiny reproducer is:
global
nbthread 1
stats socket /tmp/sock1 level admin mode 666
$ socat /tmp/sock1 - <<< "show threads"
The fix for modern versions simply consists in assigning a context to
this command from the applet storage. We're using a single int, no need
for a struct, an int* will do it. That's valid till 2.6.
Prior to 2.6, better switch to appctx->ctx.cli.i0 or i1 which are all
properly initialized before the command is executed.
This must be backported to all stable versions.
Thanks to Andjelko Horvat for the report and the reproducer.
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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.
