ResultSet.next() failed to execute #188

jkrmelj · 2022-04-11T08:44:16Z

jkrmelj
Apr 11, 2022

Hi,

using AWS mysql compatible driver, with default settings set, occasionally produces an exception within AuroraTopologyService.
The application is using multiple (Hikari) connection pools towards multiple Aurora clusters in parallel, each connection pool for each cluster.
During the workload, occasional exceptions are seen during the ResultSet.next() call:

Caused by: java.util.ConcurrentModificationException: null at java.base/java.util.LinkedHashMap$LinkedHashIterator.nextNode(LinkedHashMap.java:719) at java.base/java.util.LinkedHashMap$LinkedValueIterator.next(LinkedHashMap.java:746) at software.aws.rds.jdbc.mysql.shading.com.mysql.cj.util.ExpiringCache$1.removeEldestEntry(ExpiringCache.java:47) at java.base/java.util.LinkedHashMap.afterNodeInsertion(LinkedHashMap.java:299) at java.base/java.util.HashMap.putVal(HashMap.java:660) at java.base/java.util.HashMap.put(HashMap.java:608) at software.aws.rds.jdbc.mysql.shading.com.mysql.cj.util.ExpiringCache.put(ExpiringCache.java:109) at software.aws.rds.jdbc.mysql.shading.com.mysql.cj.jdbc.ha.plugins.failover.AuroraTopologyService.updateCache(AuroraTopologyService.java:388) at software.aws.rds.jdbc.mysql.shading.com.mysql.cj.jdbc.ha.plugins.failover.AuroraTopologyService.getTopology(AuroraTopologyService.java:198) at software.aws.rds.jdbc.mysql.shading.com.mysql.cj.jdbc.ha.plugins.failover.FailoverConnectionPlugin.updateTopologyAndConnectIfNeeded(FailoverConnectionPlugin.java:698) at software.aws.rds.jdbc.mysql.shading.com.mysql.cj.jdbc.ha.plugins.failover.FailoverConnectionPlugin.execute(FailoverConnectionPlugin.java:243) at software.aws.rds.jdbc.mysql.shading.com.mysql.cj.jdbc.ha.plugins.ConnectionPluginManager.execute(ConnectionPluginManager.java:133) at software.aws.rds.jdbc.mysql.shading.com.mysql.cj.jdbc.ha.ConnectionProxy$JdbcInterfaceProxy.invoke(ConnectionProxy.java:319) at com.sun.proxy.$Proxy279.next(Unknown Source) at com.zaxxer.hikari.pool.HikariProxyResultSet.next(HikariProxyResultSet.java)

What could be the possible reason behind this exception?