我正在写一个测试flink两步提交的案例，下面是概述。
sink kafka 曾经是Kafka的制作人。 sink step mysql是否扩展 two step commit . sink compare mysql是否扩展 two step commit ，此接收器偶尔会抛出一个exeption来模拟检查点失败。
当checkpoint失败并恢复时，我发现mysql两步提交可以正常工作，但是kafka使用者会读取上次成功的偏移量，kafka生产者会生成消息，即使他在这个checkpoint失败之前已经完成了。
在这种情况下如何避免重复消息？
谢谢你的帮助。
环境：
Flink1.9.1
java 1.8版
Kafka2.11
Kafka制作人代码：

dataStreamReduce.addSink(new FlinkKafkaProducer<>(
                "flink_output",
                new KafkaSerializationSchema<Tuple4<String, String, String, Long>>() {
                    @Override
                    public ProducerRecord<byte[], byte[]> serialize(Tuple4<String, String, String, Long> element, @Nullable Long timestamp) {
                        UUID uuid = UUID.randomUUID();
                        JSONObject jsonObject = new JSONObject();
                        jsonObject.put("uuid", uuid.toString());
                        jsonObject.put("key1", element.f0);
                        jsonObject.put("key2", element.f1);
                        jsonObject.put("key3", element.f2);
                        jsonObject.put("indicate", element.f3);
                        return new ProducerRecord<>("flink_output", jsonObject.toJSONString().getBytes(StandardCharsets.UTF_8));
                    }
                },
                kafkaProps,
                FlinkKafkaProducer.Semantic.EXACTLY_ONCE
        )).name("sink kafka");

检查点设置：

StreamExecutionEnvironment executionEnvironment = StreamExecutionEnvironment.getExecutionEnvironment();
        executionEnvironment.enableCheckpointing(10000);
        executionEnvironment.getCheckpointConfig().setTolerableCheckpointFailureNumber(0);
        executionEnvironment.getCheckpointConfig().setPreferCheckpointForRecovery(true);

mysql接收器：

dataStreamReduce.addSink(
                new TwoPhaseCommitSinkFunction<Tuple4<String, String, String, Long>,
                        Connection, Void>
                        (new KryoSerializer<>(Connection.class, new ExecutionConfig()), VoidSerializer.INSTANCE) {

                    int count = 0;
                    Connection connection;

                    @Override
                    protected void invoke(Connection transaction, Tuple4<String, String, String, Long> value, Context context) throws Exception {
                        if (count > 10) {
                            throw new Exception("compare test exception.");
                        }
                        PreparedStatement ps = transaction.prepareStatement(
                                " insert into test_two_step_compare(slot_time, key1, key2, key3, indicate) " +
                                        " values(?, ?, ?, ?, ?) " +
                                        " ON DUPLICATE KEY UPDATE indicate = indicate + values(indicate) "
                        );
                        ps.setString(1, context.timestamp().toString());
                        ps.setString(2, value.f0);
                        ps.setString(3, value.f1);
                        ps.setString(4, value.f1);
                        ps.setLong(5, value.f3);
                        ps.execute();
                        ps.close();
                        count += 1;
                    }

                    @Override
                    protected Connection beginTransaction() throws Exception {
                        LOGGER.error("compare in begin transaction");
                        try {
                            if (connection.isClosed()) {
                                throw new Exception("mysql connection closed");
                            }
                        }catch (Exception e) {
                            LOGGER.error("mysql connection is error: " + e.toString());
                            LOGGER.error("reconnect mysql connection");
                            String jdbcURI = "jdbc:mysql://";
                            Class.forName("com.mysql.jdbc.Driver");
                            Connection connection = DriverManager.getConnection(jdbcURI);
                            connection.setAutoCommit(false);
                            this.connection = connection;
                        }
                        return this.connection;
                    }

                    @Override
                    protected void preCommit(Connection transaction) throws Exception {
                        LOGGER.error("compare in pre Commit");
                    }

                    @Override
                    protected void commit(Connection transaction) {
                        LOGGER.error("compare in commit");
                        try {
                            transaction.commit();
                        } catch (Exception e) {
                            LOGGER.error("compare Commit error: " + e.toString());
                        }
                    }

                    @Override
                    protected void abort(Connection transaction) {
                        LOGGER.error("compare in abort");
                        try {
                            transaction.rollback();
                        } catch (Exception e) {
                            LOGGER.error("compare abort error." + e.toString());
                        }
                    }

                    @Override
                    protected void recoverAndCommit(Connection transaction) {
                        super.recoverAndCommit(transaction);
                        LOGGER.error("compare in recover And Commit");
                    }

                    @Override
                    protected void recoverAndAbort(Connection transaction) {
                        super.recoverAndAbort(transaction);
                        LOGGER.error("compare in recover And Abort");
                    }
                })
                .setParallelism(1).name("sink compare");