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34a150ccf5
PiBa-NL found some pathological cases where starting threads can hinder
each other and cause a measurable slow down. This problem is reproducible
with the following config (haproxy must be built with -DDEBUG_DEV) :
global
stats socket /tmp/sock1 mode 666 level admin
nbthread 64
backend stopme
timeout server 1s
option tcp-check
tcp-check send "debug dev exit\n"
server cli unix@/tmp/sock1 check
This will cause the process to be stopped once the checks are ready to
start. Binding all these to just a few cores magnifies the problem.
Starting them in loops shows a significant time difference among the
commits :
# before startup serialization
$ time for i in {1..20}; do taskset -c 0,1,2,3 ./haproxy-e186161 -db -f slow-init.cfg >/dev/null 2>&1; done
real 0m1.581s
user 0m0.621s
sys 0m5.339s
# after startup serialization
$ time for i in {1..20}; do taskset -c 0,1,2,3 ./haproxy-e4d7c9dd -db -f slow-init.cfg >/dev/null 2>&1; done
real 0m2.366s
user 0m0.894s
sys 0m8.238s
In order to address this, let's use plain mutexes and cond_wait during
the init phase. With this done, waiting threads now sleep and the problem
completely disappeared :
$ time for i in {1..20}; do taskset -c 0,1,2,3 ./haproxy -db -f slow-init.cfg >/dev/null 2>&1; done
real 0m0.161s
user 0m0.079s
sys 0m0.149s
The HAProxy documentation has been split into a number of different files for ease of use. Please refer to the following files depending on what you're looking for : - INSTALL for instructions on how to build and install HAProxy - 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)