Assigning bugs manually wastes engineering time, increases triage friction, and can slow down resolution by days. What if your system automatically suggested the right assignee for every new issue based on historical data?

In this blog post, we’ll walk through how you can train a custom machine learning model using your Jira export, Python, and scikit-learn to predict bug assignees based on issue summaries and descriptions.

AI-based defect management visual

πŸ” Why Predict Assignees?

  • πŸ”„ Multiple handoffs
  • ⏳ Increased time to resolution
  • πŸ˜“ Frustration among devs and QA teams

By applying machine learning to historical bug data, we can predict the most likely engineer for a new ticket with 80–90% accuracy (based on Bugflows' internal benchmarks). That’s hours of saved effort every week.

πŸ“ Step 1: Export Your Jira Data

First, get your Jira issues exported as CSV. You'll need at least these columns:

  • summary
  • description
  • assignee
  • created

πŸ‘‰ Jira CSV Export Docs

πŸ› οΈ Step 2: Install Python Libraries

We'll use some core data science tools:

pip install pandas scikit-learn nltk matplotlib

🧹 Step 3: Preprocess Your Data

Clean and prepare the data for modeling.

import pandas as pd
import nltk
from sklearn.model_selection import train_test_split
from sklearn.feature_extraction.text import TfidfVectorizer
from sklearn.linear_model import LogisticRegression
from sklearn.metrics import classification_report

nltk.download('stopwords')
from nltk.corpus import stopwords

df = pd.read_csv('jira_issues.csv')
df['text'] = df['summary'].fillna('') + ' ' + df['description'].fillna('')
df = df[df['assignee'].notnull()]
top_assignees = df['assignee'].value_counts().nlargest(10).index
df = df[df['assignee'].isin(top_assignees)]
X_train, X_test, y_train, y_test = train_test_split(df['text'], df['assignee'], test_size=0.2, random_state=42)
tfidf = TfidfVectorizer(stop_words=stopwords.words('english'), max_features=5000)
X_train_vec = tfidf.fit_transform(X_train)
X_test_vec = tfidf.transform(X_test)
                                                    

πŸ€– Step 4: Train the Model

We’ll use a simple but effective Logistic Regression classifier.

 model = LogisticRegression(max_iter=1000)
model.fit(X_train_vec, y_train)
y_pred = model.predict(X_test_vec)
print(classification_report(y_test, y_pred))
                                                    

Sample output:

    precision    recall  f1-score   support

  alice      0.89       0.82      0.85        45
  bob        0.76       0.88      0.81        51
  ...
accuracy                           0.84       400

                                                    

πŸ“Š Step 5: Analyze & Improve

  • Visualize confusion matrix to spot misclassifications
  • Try advanced models like RandomForestClassifier or XGBoost
  • Use Issue Type, Component, or Labels as additional features
  • Train weekly to reflect team changes

πŸ”„ Bonus: Deploy as a Microservice

You can use FastAPI to serve this model via an endpoint:

from fastapi import FastAPI
from pydantic import BaseModel
import joblib

class Bug(BaseModel):
    summary: str
    description: str

app = FastAPI()
model = joblib.load("assignee_model.pkl")
vectorizer = joblib.load("vectorizer.pkl")

@app.post("/predict")
def predict(bug: Bug):
    text = bug.summary + " " + bug.description
    vec = vectorizer.transform([text])
    pred = model.predict(vec)
    return {"predicted_assignee": pred[0]}

🧩 Real-World Examples

  • Microsoft uses ML to triage issues in large codebases
  • Facebook uses predictive tools for Messenger bugs
  • Bugflows achieves 86%+ accuracy in enterprise setups

πŸ” Key Takeaways

  • scikit-learn + TF-IDF is a powerful baseline
  • Automation = less toil, faster releases, happier engineers
  • Training weekly ensures models adapt to team changes

βš™οΈ Want This Integrated in Your Org?

Bugflows builds end-to-end ML solutions for bug data. Book a demo and get started in days.