Github user mushketyk commented on a diff in the pull request:
https://github.com/apache/flink/pull/2244#discussion_r74698018
--- Diff:
flink-streaming-connectors/flink-connector-kafka-base/src/main/java/org/apache/flink/streaming/util/serialization/JsonRowSerializationSchema.java
---
@@ -0,0 +1,69 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.flink.streaming.util.serialization;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import org.apache.flink.api.table.Row;
+import org.apache.flink.util.Preconditions;
+
+
+/**
+ * Serialization schema that serializes an object into a JSON bytes.
+ *
+ * <p>Serializes the input {@link Row} object into a JSON string and
+ * converts it into <code>byte[]</code>.
+ *
+ * <p>Result <bode>byte[]</bode> messages can be deserialized using
+ * {@link JsonRowDeserializationSchema}.
+ */
+public class JsonRowSerializationSchema implements
SerializationSchema<Row> {
+ /** Fields names in the input Row object */
+ private final String[] fieldNames;
+ /** Object mapper that is used to create output JSON objects */
+ private static ObjectMapper mapper = new ObjectMapper();
--- End diff --
It is thread-safe. Here is a quote from Jackson docs
(http://wiki.fasterxml.com/JacksonBestPracticeThreadSafety):
* Factories (ObjectMapper, JsonFactory) are thread-safe once configured: so
ensure that all configuration is done from a single thread, and before
instantiating anything with factory.
* Reader/writer instances (like JsonParser and JsonParser) are not
thread-safe -- there is usually no need for them to be, but if for some reason
you need to access them from multiple threads, external synchronization is
needed
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