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Avro2TF is designed to fill the gap of making users' training data ready to be consumed by deep learning training frameworks like TensorFlow.
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Avro2TF Build Status

Deep learning has been successfully applied to multiple AI systems at LinkedIn that are related to recommendation and search. One of the important lessons that we have learned during this journey is to provide good deep learning platforms that help our modeling engineers become more efficient and productive. Avro2TF is part of this effort to reduce the complexity of data processing and improving velocity of advanced modeling. In addition to advanced deep learning techniques, LinkedIn has been at the forefront of Machine Learning innovation for years now. We have many different ML approaches that consume large amount of data everyday. Efficiency and accuracy are the most important measurements for these approaches. To effectively support deep learning at LinkedIn, we need to first address the data processing issues. Most of the datasets used by our ML algorithms (e.g., LinkedIn’s large scale personalization engine Photon-ML) are in Avro format. Each record in a Avro dataset is essentially a sparse vector, and can be easily consumed by most of the modern classifiers. However, the format cannot be directly used by TensorFlow -- the leading deep learning package. The main blocker is that the sparse vector is not in the same format as Tensor. We believe that this is not only a LinkedIn problem, many companies have vast amount of ML data in similar sparse vector format, and Tensor format is still relatively new to many companies. Avro2TF bridges this gap by providing scalable Spark based transformation and extensions mechanism to efficiently convert the data into TF records that can be readily consumed by TensorFlow. With this technology, developers can improve their productivity by focusing on model building rather than data conversion.

Compatibility Notes

It is recommended to run Avro2TF with Scala 2.11 and above.


How to build

Avro2TF is built using Gradle. To build Avro2TF, run:

./gradlew build

This will automatically run tests, if want to build without running tests, run:

./gradlew build -x test

The jar required to run Avro2TF will be located in ./avro2tf-cli/build/libs/.


Avro2TF reads raw user input data with any format supported by Spark to generate Avro or TFRecord tensorized training data.

Avro2TF exposes to users a JSON config to specify the tensors that a modeler wants to use in training. For each tensor, a user should specify two kinds of information:

  1. What existing features are used to construct the tensor.
  2. The expected name, dtype, and shape of the tensor.

Input Data Requirements

We support all data format that Spark can read, including the most popular formats Avro and ORC. For categorical/sparse features, we require them represented in NTV (name-term-value) format.

The type of a single categorical/sparse feature will have a type of Array[NTV]. We treat Array[NTV] as a special primitive type. Thus, the supported input primitive types include:

  1. long
  2. float
  3. double
  4. String
  5. bytes (for multimedia data such as image, audio, and video)
  6. boolean
  7. Array[NTV]

Arrays of primitive types with any rank are supported.

Supported Data Types of Output Tensor

In Avro2TF, the supported data types (dtype) of output tensors are: int, long, float, double, string, boolean, bytes. We also provide a special data type: sparseVector to represent categorical/sparse features. A sparseVector tensor type has two fields: indices and values.

In the below table, we list the corresponding data types after loading the serialized tensors in Avro2TF to TensorFlow. In TensorFlow, bytes is represented using tf.string and users can later decode it to images, audios, etc. The sparseVector type will be converted to tf.SparseTensor.

Data type of serialized tensor in Avro2TF Data type of deserialized tensor in TensorFlow
int tf.int32
long tf.int64
float tf.float32
double tf.float64
String tf.string
bytes tf.string
boolean tf.bool
sparseVector tf.SparseTensor

Avro2TF Configuration

The below table shows all the available configuration names and their detailed explanation.

Name Required? Default Value Meaning
features yes / A list of tensor configs. Each config includes inputFeatureInfo and outputTensorInfo. Must not be empty.
labels no None A list of tensor configs.
inputFeatureInfo no {“columnExpr” : ${}} Specify input features used to construct a tensor.
columnExpr no None Spark SQL column expression. If both columnExpr and columnConfig do not exist, columnExpr will have a default {“columnExpr” : ${}} value.
columnConfig no None Only for extracting NTV features. A user should not specify both columnExpr and columnConfig.
transformConfig no None Specify transformations applied on input features, available transformers: hashing and tokenization.
hashInfo no None Specify hashing related information.
hashBucketSize yes / The bucket size of the hash function.
numHashFunctions no 1 The number of hash functions used (only salt will be different).
combiner no SUM How to merge the values of repeated indices in a sparse vector (AVG, SUM, MAX).
tokenization no None Tokenization related configs.
removeStopWords no false Whether to remove stop words during tokenization.
outputTensorInfo yes / Info on expected output tensor.
name yes / Name of output tensor.
dtype yes / The expected dtype of output tensor.
shape no [] The expected shape of output tensor, examples: []: scalar; sparse vector; [-1] : 1D array of any length; [6]: 1D array with size 6; [2, 3]: matrix with 2 rows and 3 columns.

Avro2TF Examples

Please take a look at our Avro2TF Official Tutorial! :)

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