Which background task looks for pg_xlog in 10?

[Johann Spies]

I see this in /var/log/postgresql/postgresql-10-main.log:

postgres postgres@template1 ERROR:  could not open directory
"pg_xlog": No such file or directory

postgres postgres@template1 STATEMENT:  SELECT count(*) AS segments
FROM pg_ls_dir('pg_xlog') t(fn) \
WHERE fn ~ '^[0-9A-Z]{24}$'

Where does this come from?

Regards
Johann
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