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The new 'close-spread-time' global option can be used to spread idle and active HTTP connction closing after a SIGUSR1 signal is received. This allows to limit bursts of reconnections when too many idle connections are closed at once. Indeed, without this new mechanism, in case of soft-stop, all the idle connections would be closed at once (after the grace period is over), and all active HTTP connections would be closed by appending a "Connection: close" header to the next response that goes over it (or via a GOAWAY frame in case of HTTP2). This patch adds the support of this new option for HTTP as well as HTTP2 connections. It works differently on active and idle connections. On active connections, instead of sending systematically the GOAWAY frame or adding the 'Connection: close' header like before once the soft-stop has started, a random based on the remainder of the close window is calculated, and depending on its result we could decide to keep the connection alive. The random will be recalculated for any subsequent request/response on this connection so the GOAWAY will still end up being sent, but we might wait a few more round trips. This will ensure that goaways are distributed along a longer time window than before. On idle connections, a random factor is used when determining the expire field of the connection's task, which should naturally spread connection closings on the time window (see h2c_update_timeout). This feature request was described in GitHub issue #1614. This patch should be backported to 2.5. It depends on "BUG/MEDIUM: mux-h2: make use of http-request and keep-alive timeouts" which refactorized the timeout management of HTTP2 connections.
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)