[pgpool-general: 6778] Delay in synchronous replication, is it possible ?!

[Franklin Anderson de Oliveira Souza]

I use pgpool with 5 slave on mode synchronous.
But sometimes i see values on column replication_delay when execute command
show pool_nodes.
Sometimes, when a node goes beyond the value of delay_threshold, the node
does not receive balancing query.

But
1- Synchronous replication should not be delayed is not it?
2- How is this possible ?
3- Is the replication_delay parameter of pgpool wrong?

show pool_nodes
 node_id |  hostname   | port | status | lb_weight |  role   | select_cnt |
load_balance_node | replication_delay | last_status_change
---------+-------------+------+--------+-----------+---------+------------+-------------------+-------------------+---------------------
 0       | IP          | 5432 | up     | 0.100000  | primary | 230616548  |
false             | 0                 | 2019-10-24 19:17:27
 1       | IP          | 5432 | up     | 0.100000  | standby | 172466610  |
true              | 0                 | 2019-10-24 19:17:27
 2       | IP          | 5432 | up     | 0.100000  | standby | 180179200  |
false             | 234324            | 2019-10-24 19:17:27
 3       | IP          | 5432 | up     | 0.100000  | standby | 178475037  |
false             | 20777216          | 2019-10-24 19:17:27
 4       | IP          | 5432 | up     | 0.100000  | standby | 182174042  |
false             | 0                 | 2019-10-24 19:17:27
 5       | IP          | 5432 | up     | 0.100000  | standby | 181169375  |
false             | 0                 | 2019-10-24 19:17:27



pg_stat_replication
  application_name  | client_addr |  write_lsn   |  flush_lsn   |
write_lag    | sync_priority | sync_state
--------------------+-------------+--------------+--------------+-----------------+---------------+------------
 pje1_slave1        | IP          | 8FA/42E88B60 | 8FA/42E88B60 |
00:00:00.000355 |             1 | sync
 pje1_slave2        | IP          | 8FA/42E88B60 | 8FA/42E88B60 |
00:00:00.000312 |             2 | potential
 pje1_slave3        | IP          | 8FA/42E88B60 | 8FA/42E88B60 |
00:00:00.000366 |             3 | potential
 pje1_slave4        | IP          | 8FA/42E88B60 | 8FA/42E88B60 |
00:00:00.000277 |             4 | potential
 pje1_slave5        | IP          | 8FA/42E88B60 | 8FA/42E88B60 |
00:00:00.000265 |             5 | potential

-- 
foobar
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