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https://issues.apache.org/jira/browse/KAFKA-5953?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16191824#comment-16191824
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Randall Hauch commented on KAFKA-5953:
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[~jpechane] wrote:
{quote}
As a result a DriverManager calls ServiceLoader and searches for all JDBC
drivers. The postgres driver from connector 2) is found associated with
classloader from connector 1).
{quote}
The DriverManager will call ServiceLoader to search for all JDBC drivers the
first time the DriverManager is loaded. If Connect loads connector 1 first,
then the DriverManager would search the classpath that includes the plugin for
connector 1, but I don't understand how/why it would find the driver for
connector 2 since that plugin's classloader is not used at this point. It does
make sense, however, that once connector 2 is loaded, it would not find the
PostgreSQL driver because the DriverManager has already called ServiceLoader
and will not search the new classloader.
> Connect classloader isolation may be broken for JDBC drivers
> ------------------------------------------------------------
>
> Key: KAFKA-5953
> URL: https://issues.apache.org/jira/browse/KAFKA-5953
> Project: Kafka
> Issue Type: Bug
> Components: KafkaConnect
> Affects Versions: 0.11.0.0
> Reporter: Jiri Pechanec
> Priority: Critical
>
> Let's suppose there are two connectors deployed
> # using JDBC driver (Debezium MySQL connector)
> # using PostgreSQL JDBC driver (JDBC sink).
> Connector 1 is started first - it executes a statement
> {code:java}
> Connection conn = DriverManager.getConnection(url, props);
> {code}
> As a result a {{DriverManager}} calls {{ServiceLoader}} and searches for all
> JDBC drivers. The postgres driver from connector 2) is found associated with
> classloader from connector 1).
> Connector 2 is started after that - it executes a statement
> {code:java}
> connection = DriverManager.getConnection(url, username, password);
> {code}
> DriverManager finds the connector that was loaded in step before but becuase
> the classloader is different - now we use classloader 2) so it refuses to
> load the class and no JDBC driver is found.
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