Close connections marked as evicted instead of returning them to the pool #2157
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Foulest
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May 5, 2024
- Pulled changes from brettwooldridge#2189 brettwooldridge#2180 brettwooldridge#2157 brettwooldridge#2149 brettwooldridge#2147 brettwooldridge#2133 brettwooldridge#2068 brettwooldridge#2065 brettwooldridge#2038 brettwooldridge#2035 brettwooldridge#2031 brettwooldridge#2010 (aside from code found in removed test functions)
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Description
According to the documentation, connections that were in use during a soft eviction, are effectively evicted when returned to the pool. See Javadoc of
com.zaxxer.hikari.HikariPoolMXBean.softEvictConnectionsThat's not how it's currently implemented though. Connections that are marked as evicted are being closed when the connection is tried to be borrowed from the pool.
With this PR, connections marked as evicted are additionally closed when returned to the pool.
Because of race conditions, it's still possible that connections that are marked as evicted are being returned to the pool.
Therefore, I left the logic in
com.zaxxer.hikari.pool.HikariPool.getConnection(long)as is.Why?
We use a database cluster in an active/passive setup. The JDBC connection string ensures that connections are always established with the active node.
On database maintenance we are able to switch the roles of the nodes. We then want to evict all current connections (connected to the now passive node) to ensure that new connections are established with the now active node.
With low volume of SQL executions it can take some time until a connection marked as evicted is being borrowed from the pool.
We would therefore have to adjust the minimumIdleTime to ensure that connections are being re-established in a timely manner.