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a57f2a5cfe
In order to limit inter-thread contention on the global pool, in 2.9-dev3
with commit 7bf829ace ("MAJOR: pools: move the shared pool's free_list
over multiple buckets"), it was decided that if the selected bucket had
an empty free list, we would simply give up and fall back to the OS
allocator.
But this causes allocations to be made from the OS for certain threads,
to be released to overloaded pools that are sent back to the OS. One
visible effect is that sending a lot of traffic using h2load with 100
parallel streams over 100 connections causes 5-10k buffers to be
allocated, then reducing the load to only 10 connections doesn't make
these allocations go down, just because some buckets are no longer
visited.
Tests show that giving a second chance to pick another bucket in this
case is sufficient to visit all other buckets and recycle their pending
objects. Now "show pools" that starts at 10k buffers at 100 connections
goes down to about 150 with 1 connection and 100 streams in a fraction
of a second.
No backport is needed, as the issue is only in 2.9.
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)