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Based on Willy's idea (from 3.0-dev6 announcement message): in this patch we try to reduce the max latency that can be caused by running lua scripts with default settings. Indeed, by default, hlua engine is allowed to process up to 10k instructions per batch. While this value was found to be the optimal one for a single thread, it turns out that keeping a thread busy for 10k lua instructions could increase thread contention. This is especially true when the script is loaded with 'lua-load', because in that case the current thread owns the main lua lock and prevent other threads from making any progress if they're also waiting on the main lock. Thanks to Thierry Fournier's work, we know that performance-wise we can reach optimal performance by sticking between 500 and 10k instructions per batch. Given that, when the script is loaded using 'lua-load', if no "tune.lua.forced-yield" was set by the user, we automatically divide the default value (10K) by the number of threads haproxy can use to reduce thread contention (given that all threads could compete for the main lua lock), however we make sure not to return a value below 500, because Thierry's work showed that this would come with a significant performance loss. The historical behavior may still be enforced by setting "tune.lua.forced-yield" to 10000 in the global config section.
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 - 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)