Postgres Adatper SQL Plugin and Nil Pointer Exception

[chris-selinc]

FluentD verison: fluentd 1.17.1
Ruby version: ruby 3.2.5 (2024-07-26 revision 31d0f1a2e7) [x86_64-linux]
Gems:
fluent-plugin-sql (2.3.1)
pg (1.5.9)
This is currently running in a k3s environment.

When using the following configuration for the source in and FluentD:

    <source>
      @type sql
      adapter postgresql
      host hostname-of-postgres
      port 5432
      database databaseName
      username userName
      password passwordForDatabase
      tag_prefix postgres
      select_interval 5s
      state_file /var/run/fluentd/sql_state
      <table>
        table target_table
        tag target_table
        update_column insertTimestamp
      </table>
    </source>

Sometimes I am able to successfully query the database, and other times I am unable to query the database, which results in the following error:

        line = caller(depth+1)[0]
                              ^^^
        from /usr/local/bundle/gems/fluentd-1.17.1/lib/fluent/log.rb:506:in `dump_stacktrace'
        from /usr/local/bundle/gems/fluentd-1.17.1/lib/fluent/log.rb:389:in `warn_backtrace'
        from /usr/local/bundle/gems/fluentd-1.17.1/lib/fluent/root_agent.rb:287:in `rescue in block (3 levels) in shutdown'
        from /usr/local/bundle/gems/fluentd-1.17.1/lib/fluent/root_agent.rb:266:in `block (3 levels) in shutdown'
/usr/local/bundle/gems/fluent-plugin-sql-2.3.1/lib/fluent/plugin/in_sql.rb:252:in `shutdown': undefined method `join' for nil:NilClass (NoMethodError)

      @thread.join

Sometimes the plugin works as expected, and then I'm able to successfully print out the results.