Autovacuum of pg_shdepend

Hello,

we have a strange problem with autovacuum. We have three workers, but
usually only one works and two are waiting as they are all trying to
process table pg_shdepend which is shared between all databases.

We have two clusters, both have a few thousands of databases. Because of
this problem the autovacuum process can't keep up and the planner uses
old data causing large impact on the performance.

Is there a way to prevent this behaviour, please?

With regards

Ondřej Světlík