pgsql: Doc: document possible need to raise kernel's somaxconn limit.

Doc: document possible need to raise kernel's somaxconn limit.

On fast machines, it's possible for applications such as pgbench
to issue connection requests so quickly that the postmaster's
listen queue overflows in the kernel, resulting in unexpected
failures (with not-very-helpful error messages). Most modern OSes
allow the queue size to be increased, so document how to do that.

Per report from Kevin McKibbin.

Discussion: /messages/by-id/CADc_NKg2d+oZY9mg4DdQdoUcGzN2kOYXBu-3--RW_hEe0tUV=g@mail.gmail.com

Branch
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REL_15_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/2c63b0930aee1bb5c265fad4a65c9d0b62b1f9da

Modified Files
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doc/src/sgml/runtime.sgml | 16 ++++++++++++++++
1 file changed, 16 insertions(+)