If you fork before making any connections, you should be fine.

If you make a connection first and then fork, you probably have different children trying to share a single database connection. That's not going to work. What you may want to do is have the children clone the parent's database connection or use connect instead of connect_cached. Either way, the parent's database connection has to be disposed of properly in the child.

$parent_dbh->{InactiveDestroy} = 1;
undef $parent_dbh;
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There's an example in DBI, fork, and clone.