b81ab159a6
Jacques Heunis from bloomberg reported on the mailing list [1] that
with haproxy 2.8 up to master, yielding from a Lua tcp service while
data was still buffered inside haproxy would eat some data which was
definitely lost.
He provided the reproducer below which turned out to be really helpful:
global
log stdout format raw local0 info
lua-load haproxy_yieldtest.lua
defaults
log global
timeout connect 10s
timeout client 1m
timeout server 1m
listen echo
bind *:9090
mode tcp
tcp-request content use-service lua.print_input
haproxy_yieldtest.lua:
core.register_service("print_input", "tcp", function(applet)
core.Info("Start printing input...")
while true do
local inputs = applet:getline()
if inputs == nil or string.len(inputs) == 0 then
core.Info("closing input connection")
return
end
core.Info("Received line: "..inputs)
core.yield()
end
end)
And the script below:
#!/usr/bin/bash
for i in $(seq 1 9999); do
for j in $(seq 1 50); do
echo "${i}_foo_${j}"
done
sleep 2
done
Using it like this:
./test_seq.sh | netcat localhost 9090
We can clearly see the missing data for every "foo" burst (every 2
seconds), as they are holes in the numbering.
Thanks to the reproducer, it was quickly found that only versions
>= 2.8 were affected, and that in fact this regression was introduced
by commit 31572229e ("MEDIUM: hlua/applet: Use the sedesc to report and
detect end of processing")
In fact in 31572229e 2 mistakes were made during the refaco.
Indeed, both in hlua_applet_tcp_fct() (which is involved in the reproducer
above) and hlua_applet_http_fct(), the request (buffer) is now
systematically consumed when returning from the function, which wasn't the
case prior to this commit: when HLUA_E_AGAIN is returned, it means a
yield was requested and that the processing is not done yet, thus we
should not consume any data, like we did prior to the refacto.
Big thanks to Jacques who did a great job reproducing and reporting this
issue on the mailing list.
[1]: https://www.mail-archive.com/haproxy@formilux.org/msg45778.html
It should be backported up to 2.8 with commit 31572229e
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.