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ed3e4f33fd
Adds new live updatable config: uninitialized_connections_semaphore_cpu_concurrency. It should help to reduce cpu usage by limiting cpu concurrency for new connections. As a last resort when those connections are waiting for initial processing too long (over 1m) they are shed. New connections_shed and connections_blocked metrics are added for tracking. Testing: - manually via simple program creating high number of connection and constantly re-connecting - added benchmark Following are benchmark results: Before: ``` > build/release/test/perf/perf_generic_server --smp=1 170101.41 tps ( 13.1 allocs/op, 0.0 logallocs/op, 7.0 tasks/op, 4695 insns/op, 3178 cycles/op, 0 errors) [...] throughput: mean=173850.06 standard-deviation=1844.48 median=174509.66 median-absolute-deviation=874.23 maximum=175087.49 minimum=170588.54 instructions_per_op: mean=4725.59 standard-deviation=13.35 median=4729.38 median-absolute-deviation=12.49 maximum=4738.61 minimum=4709.96 cpu_cycles_per_op: mean=3135.08 standard-deviation=32.13 median=3122.68 median-absolute-deviation=22.29 maximum=3179.38 minimum=3103.15 ``` After: ``` > build/release/test/perf/perf_generic_server --smp=1 167373.19 tps ( 13.1 allocs/op, 0.0 logallocs/op, 7.0 tasks/op, 4821 insns/op, 3371 cycles/op, 0 errors) [...] throughput: mean= 171199.55 standard-deviation=2484.58 median= 171667.06 median-absolute-deviation=2087.63 maximum=173689.11 minimum=167904.76 instructions_per_op: mean= 4801.90 standard-deviation=16.54 median= 4796.78 median-absolute-deviation=9.32 maximum=4830.71 minimum=4789.81 cpu_cycles_per_op: mean= 3245.26 standard-deviation=32.28 median= 3230.44 median-absolute-deviation=16.52 maximum=3297.39 minimum=3215.62 ``` The patch adds around 67 insns/op so it's effect on performance should be negligible. Fixes: https://github.com/scylladb/scylladb/issues/22844 Closes scylladb/scylladb#22828 * github.com:scylladb/scylladb: transport: move on_connection_close into connection destructor test: perf: make aggregated_perf_results formatting more human readable transport: add blocked and shed connection metrics generic_server: throttle and shed incoming connections according to semaphore limit generic_server: add data source and sink wrappers bookkeeping network IO generic_server: coroutinize part of server::do_accepts test: add benchmark for generic_server test: perf: add option to count multiple ops per time_parallel iteration generic_server: add semaphore for limiting new connections concurrency generic_server: add config to the constructor generic_server: add on_connection_ready handler