On Mon, Dec 14, 2020 at 8:03 PM Fujii Masao <masao.fu...@oss.nttdata.com> wrote: > > We will not output if the invalidated entry has no active connection[2], so > > if we fix the connection leak issue with the above discussed fix i.e > > closing all the invalidated connections at the end of next xact, there are > > less chances that we will output invalidated entries in the > > postgres_fdw_get_connections() output. Only case we may show up invalidated > > connections(which have active connections entry->conn) in the > > postgres_fdw_get_connections() output is as follows: > > > > 1) say we have few cached active connections exists in session 1 > > 2) drop the user mapping (in another session) associated with any of the > > cached connections to make that entry invalid > > 3) run select * from postgres_fdw_get_connections(); in session 1. At the > > start of the xact, the invalidation message gets processed and the > > corresponding entry gets marked as invalid. If we allow invalid connections > > (that have entry->conn) to show up in the output, then we show them in the > > result of the query. At the end of xact, we close these invalid > > connections, in this case, user might think that he still have invalid > > connections active. > > What about the case where the transaction started at the above 1) at session > 1, and postgres_fdw_get_connections() in the above 3) is called within that > transaction at session 1? In this case, postgres_fdw_get_connections() can > return even invalidated connections?
In that case, since the user mapping would have been dropped in another session and we are in the middle of a txn in session 1, the entries would not get marked as invalid until the invalidation message gets processed by the session 1 which may happen if the session 1 opens a sub txn, if not then for postgres_fdw_get_connections() the entries will still be active as they would not have been marked as invalid yet and postgres_fdw_get_connections() would return them in the output. With Regards, Bharath Rupireddy. EnterpriseDB: http://www.enterprisedb.com
