[GENERAL] pg_basebackup error: replication slot "pg_basebackup_2194" already exists

I ran into the issue described below with 10.0 beta. The error I got is:

pg_basebackup: could not create temporary replication slot
"pg_basebackup_2194": ERROR:  replication slot "pg_basebackup_2194"
already exists

A race condition? Or maybe I am doing something wrong.





Release:
    Name        : postgresql10-server
    Version     : 10.0
    Release     : beta1PGDG.rhel7


Test Type:
    Functional testing of a pacemaker resource agent
(https://github.com/ulodciv/pgha)


Test Detail:
    During context/environement setup, pg_basebackup is invoked (in
parallel) from multiple virtual machines. The backups are then started
as asynchronously replicated hot standbies.


Platform:
    Centos 7.3


Installation Method:
    yum -y install
https://download.postgresql.org/pub/repos/yum/testing/10/redhat/rhel-7-x86_64/pgdg-redhat10-10-1.noarch.rpm
    yum -y install postgresql10-server postgresql10-contrib


Platform Detail:


Test Procedure:

    Have pg_basebackup run simultaneously on multiple hosts against
the same instance eg:

        pg_basebackup -h test4 -p 5432 -D /var/lib/pgsql/10/data -U repl1 -Xs


Failure?

E               deploylib.deployer_error.DeployerError:
postgres@test5: got exit status 1 for:
E               pg_basebackup -h test4 -p 5432 -D
/var/lib/pgsql/10/data -U repl1 -Xs
E               stderr: pg_basebackup: could not create temporary
replication slot "pg_basebackup_2194": ERROR:  replication slot
"pg_basebackup_2194" already exists
E               pg_basebackup: child process exited with error 1
E               pg_basebackup: removing data directory "/var/lib/pgsql/10/data"


Test Results:


Comments:
    This seems to be new with 10. I recently began testing the
pacemaker resource agent against PG 10. I never had (or noticed) this
failure with 9.6.1 and 9.6.2.

--
Ludovic