code: protected void closeConnection(DatabaseConnection connection) throws SQLException {
  		// this can return null if we are closing the pool
  		ConnectionMetaData meta = connectionMap.remove(connection);
  		IOUtils.closeThrowSqlException(connection, "SQL connection");
  		logger.debug("closed connection {}", meta);
  		closeCount++;
  	}
docs: This should be inside of synchronized (lock) stanza.