question regarding connection failover URL postgresql 9.6 (master/slave)

Hello

question regarding connection failover URL postgresql 9.6 (master/slave), when a node( SLAVE per se) does down connections failover MASTER as expected but ONE WAY ONLY!!, if we restart SLQVE service connections never recover back.

stack: postgresql 9.6 (master/slave) + jdbc driver 9.4-1211 + tomcat7 + jdk7 + built-in ConnectionPool

ref:  https://jdbc.postgresql.org/documentation/head/connect.html      (bottom section)

Issue:  upon having MASTER + SLAVE services running , we segregate via two DataSources to point to 1st: MASTER and 2nd:

url="jdbc:postgresql://MASTER:5432,SLAVE:5432/XXDB?targetServerType=preferSlave"

when stopping SLAVE service connections failover MASTER as expected, but it seems to be a one way failover, if I restart SLAVE service it never fails back to SLAVE (unless we restart Tomcat service)

I played around with other parameters hostRecheckSeconds and loadBalanceHosts as well as changing order url="SLAVE,MASTER?targetServerType=preferSlave" as well but same thing.

 

Your helps is extremely appreciated!! thanks in advance.......

Sincerely,
Martin