DeepBugs is a framework for learning bug detectors from an existing code corpus.
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DeepBugs: Deep Learning to Find Bugs

DeepBugs is a framework for learning name-based bug detectors from an existing code corpus. See our OOPSLA 2018 paper for a detailed description.


  • All commands are called from the main directory.
  • Python code (most of the implementation) and JavaScript code (for extracting data from .js files) are in the /python and /javascript directories.
  • All data to learn from, e.g., .js files are expected to be in the /data directory.
  • All data that is generated, e.g., intermediate representations, are written into the main directory. It is recommended to move them into separate directories.
  • All generated data files have a timestamp as part of the file name. Below, all files are used with *. When running commands multiple times, make sure to use the most recent files.


  • Node.js
  • npm modules (install with npm install module_name): acorn, estraverse, walk-sync
  • Python 3
  • Python packages: keras, scipy, numpy, sklearn

JavaScript Corpus

  • The full corpus can be downloaded here and is expected to be stored in data/js/programs_all. It consists of 100.000 training files, listed in data/js/programs_training.txt, and 50.000 files for validation, listed in data/js/programs_eval.txt.
  • This repository contains only a very small subset of the corpus. It is stored in data/js/programs_50. Training and validation files for the small corpus are listed in data/js/programs_50_training.txt and data/js/programs_50_eval.txt.

Learning a Bug Detector

Creating a bug detector consists of two main steps:

  1. Extract positive (i.e., likely correct) and negative (i.e., likely buggy) training examples from code.
  2. Train a classifier to distinguish correct from incorrect code examples.

Each bug detector addresses a particular bug pattern, e.g.:

  • The SwappedArgs bug detector looks for accidentally swapped arguments of a function call, e.g., calling setPoint(y,x) instead of setPoint(x,y).
  • The BinOperator bug detector looks for incorrect operators in binary operations, e.g., i <= len instead of i < len.
  • The IncorrectBinaryOperand bug detector looks for incorrect operands in binary operations, e.g., height - x instead of height - y.

Step 1: Extract positive and negative training examples

node javascript/extractFromJS.js calls --parallel 4 data/js/programs_50_training.txt data/js/programs_50

  • The --parallel argument sets the number of processes to run.
  • programs_50_training.txt contains files to include (one file per line). To extract data for validation, run the command with data/js/programs_50_eval.txt.
  • The last argument is a directory that gets recursively scanned for .js files, considering only files listed in the file provided as the second argument.
  • The command produces calls_*.json files, which is data suitable for the SwappedArgs bug detector. For the other bug two detectors, replace calls with binOps in the above command.

Step 2: Train a classifier to identify bugs

python3 python/ SwappedArgs --learn token_to_vector.json type_to_vector.json node_type_to_vector.json --trainingData calls_xx*.json --validationData calls_yy*.json

  • The first argument selects the bug pattern.
  • The next three arguments are vector representations for tokens (here: identifiers and literals), for types, and for AST node types. These files are provided in the repository.
  • The remaining arguments are two lists of .json files. They contain the training and validation data extracted in Step 1.
  • After learning the bug detector, the command measures accurracy and recall w.r.t. seeded bugs and writes a list of potential bugs in the unmodified validation code (see poss_anomalies.txt).

Note that learning a bug detector from the very small corpus of 50 programs will yield a classifier with low accuracy that is unlikely to be useful. To leverage the full power of DeepBugs, you'll need a larger code corpus, e.g., the JS150 corpus mentioned above.

Embeddings for Identifiers

The above bug detectors rely on a vector representation for identifier names and literals. To use our framework, the easiest is to use the shipped token_to_vector.json file. Alternatively, you can learn the embeddings via Word2Vec as follows:

  1. Extract identifiers and tokens:

node javascript/extractFromJS.js tokens --parallel 4 data/js/programs_50_training.txt data/js/programs_50

  • The command produces tokens_*.json files.
  1. Encode identifiers and literals with context into arrays of numbers (for faster reading during learning):

python3 python/ tokens_*.json

  • The arguments are the just created files.
  • The command produces encoded_tokens_*.json files and a file token_to_number_*.json that assigns a number to each identifier and literal.
  1. Learn embeddings for identifiers and literals:

python3 python/ token_to_number_*.json encoded_tokens_*.json

  • The arguments are the just created files.
  • The command produces a file token_to_vector_*.json.