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, weβll 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.

π Why Predict Assignees?
- π Multiple handoffs
- β³ Increased time to resolution
- π 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 80β90% accuracy (based on Bugflows' internal benchmarks). Thatβs hours of saved effort every week.
π 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
π Jira CSV Export Docs
π οΈ Step 2: Install Python Libraries
We'll use some core data science tools:
pip install pandas scikit-learn nltk matplotlib
π§Ή 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)
π€ Step 4: Train the Model
Weβll 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
π 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
π 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]}
π§© 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
π 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
βοΈ Want This Integrated in Your Org?
Bugflows builds end-to-end ML solutions for bug data. Book a demo and get started in days.