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When an outgoing HTX message is formatted before sending it, a trash chunk is used to do the formatting. Its content is then copied into the output buffer of the H1 connection. There are some tricks to avoid this last copy. First, if possible we perform a zero-copy by swapping the area of the HTX buffer with the one of the output buffer. If zero-copy is not possible, but if the output buffer is empty, we don't use a trash chunk. To do so, we change the area of the trash chunk to point on the one of the output buffer. But it is terribly wrong. Trash chunks are global variables, allocated statically. If the area is changed, the old one is lost. Worst, the area of the output buffer is dynamically allocated, so it is released when emptied, leaving the trash chunk with a freed area (in fact, it is a bit more complicated because buffers are allocated from a memory pool). So, honestly, I don't know why we never experienced any problem because this bug till now. To fix it, we still use a temporary buffer, but we assign it to a trash chunk only when other solutions were excluded. This way, we never overwrite the area of a trash chunk. This patch must be backported to 2.0 and 1.9.
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)