I've upgraded the "org.mariadb.jdbc" % "mariadb-java-client" connector from 1.5.9 to 1.6.0 and I'd started to fail while connecting to the DB due to timeout exceptions.
I'm using it with HikariCP 2.5.1 and Slick 3.2.0. If I rollback the change again to MariaDB connector 1.5.9 it successfully connects, and if I try to upgrade directly to 2.0.1, it fails with the very same error.
The thing is that based on the 1.6.0 changelog, we shouldn't experiment any breaking change. But according to the differences in the GitHub repository, it could have some more modifications than the ones specified in the changelog :/
Exception with a local DB:
java.sql.SQLTransientConnectionException: xxx.db - Connection is not available, request timed out after 5006ms.
at com.zaxxer.hikari.pool.HikariPool.createTimeoutException(HikariPool.java:548)
at com.zaxxer.hikari.pool.HikariPool.getConnection(HikariPool.java:186)
at com.zaxxer.hikari.pool.HikariPool.getConnection(HikariPool.java:145)
at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:83)
at slick.jdbc.hikaricp.HikariCPJdbcDataSource.createConnection(HikariCPJdbcDataSource.scala:18)
at slick.jdbc.JdbcBackend$BaseSession.<init>(JdbcBackend.scala:439)
at slick.jdbc.JdbcBackend$DatabaseDef.createSession(JdbcBackend.scala:47)
at slick.jdbc.JdbcBackend$DatabaseDef.createSession(JdbcBackend.scala:38)
at slick.basic.BasicBackend$DatabaseDef$class.acquireSession(BasicBackend.scala:218)
at slick.jdbc.JdbcBackend$DatabaseDef.acquireSession(JdbcBackend.scala:38)
at slick.basic.BasicBackend$DatabaseDef$$anon$2.run(BasicBackend.scala:239)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.sql.SQLNonTransientConnectionException: Could not connect to address=(host=localhost)(port=3306)(type=master) : Connection refused
at org.mariadb.jdbc.internal.util.exceptions.ExceptionMapper.get(ExceptionMapper.java:156)
at org.mariadb.jdbc.internal.util.exceptions.ExceptionMapper.getException(ExceptionMapper.java:118)
at org.mariadb.jdbc.internal.util.exceptions.ExceptionMapper.throwException(ExceptionMapper.java:92)
at org.mariadb.jdbc.Driver.connect(Driver.java:108)
at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:95)
at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:101)
at com.zaxxer.hikari.pool.PoolBase.newConnection(PoolBase.java:341)
at com.zaxxer.hikari.pool.PoolBase.newPoolEntry(PoolBase.java:193)
at com.zaxxer.hikari.pool.HikariPool.createPoolEntry(HikariPool.java:430)
at com.zaxxer.hikari.pool.HikariPool.access$500(HikariPool.java:64)
at com.zaxxer.hikari.pool.HikariPool$PoolEntryCreator.call(HikariPool.java:570)
at com.zaxxer.hikari.pool.HikariPool$PoolEntryCreator.call(HikariPool.java:563)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
... 3 common frames omitted
Caused by: java.sql.SQLException: Could not connect to address=(host=localhost)(port=3306)(type=master) : Connection refused
at org.mariadb.jdbc.internal.protocol.AbstractConnectProtocol.connectWithoutProxy(AbstractConnectProtocol.java:1020)
at org.mariadb.jdbc.internal.util.Utils.retrieveProxy(Utils.java:481)
at org.mariadb.jdbc.Driver.connect(Driver.java:103)
... 12 common frames omitted
Caused by: java.net.ConnectException: Connection refused
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
at java.net.Socket.connect(Socket.java:589)
at java.net.Socket.connect(Socket.java:538)
at org.mariadb.jdbc.internal.protocol.AbstractConnectProtocol.connect(AbstractConnectProtocol.java:392)
at org.mariadb.jdbc.internal.protocol.AbstractConnectProtocol.connectWithoutProxy(AbstractConnectProtocol.java:1013)
... 14 common frames omitted
Exception with a remote DB:
java.sql.SQLTransientConnectionException: xxx.db - Connection is not available, request timed out after 5003ms.
at com.zaxxer.hikari.pool.HikariPool.createTimeoutException(HikariPool.java:548)
at com.zaxxer.hikari.pool.HikariPool.getConnection(HikariPool.java:186)
at com.zaxxer.hikari.pool.HikariPool.getConnection(HikariPool.java:145)
at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:83)
at slick.jdbc.hikaricp.HikariCPJdbcDataSource.createConnection(HikariCPJdbcDataSource.scala:18)
at slick.jdbc.JdbcBackend$BaseSession.<init>(JdbcBackend.scala:439)
at slick.jdbc.JdbcBackend$DatabaseDef.createSession(JdbcBackend.scala:47)
at slick.jdbc.JdbcBackend$DatabaseDef.createSession(JdbcBackend.scala:38)
at slick.basic.BasicBackend$DatabaseDef$class.acquireSession(BasicBackend.scala:218)
at slick.jdbc.JdbcBackend$DatabaseDef.acquireSession(JdbcBackend.scala:38)
at slick.basic.BasicBackend$DatabaseDef$$anon$2.run(BasicBackend.scala:239)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Disclaimer: I am one of the mariadb developper
In 1.6.0 version, "usePipelineAuth" option has changed the connection implementation.
During connection, different queries are executed. When option is active those queries are send using pipeline (all queries are send, then only all results are reads), permitting faster connection creation.
That permit to saving network latency.
Disabling this option will probably solved your issue.
At the same time, i've create an issue on mariadb tracker.