pgsql: Choose ports for test servers less likely to result in conflicts

Choose ports for test servers less likely to result in conflicts

If we choose ports in the range typically used for ephemeral ports there
is a danger of encountering a port conflict due to a race condition
between the time we choose the port in a range below that typically used
to allocate ephemeral ports, but higher than the range typically used by
well known services.

Author: Jelte Fenema-Nio, with some editing by me.

Discussion: https://postgr.es/m/d6ee8761-39d1-0033-1afb-d5a57ee056f2@gmail.com

Backpatch to all live branches (12 and up)

Branch
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REL_12_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/8398485957b630a6686cb83b67a17c75dc6ec54b

Modified Files
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src/test/perl/PostgresNode.pm | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)