Why this matters
Failing to clean up ThreadLocal variables can cause memory leaks in long-running applications, especially when using thread pools.
ThreadLocal Variables Are Properly CleanedEnsure that ThreadLocal variables are cleaned using .remove() to avoid memory leaks.
Failing to clean up ThreadLocal variables can cause memory leaks in long-running applications, especially when using thread pools.
Side-by-side examples engineers can pattern-match during review.
public class ThreadLocalUserSession implements UserSession {
private static final ThreadLocal<UserSession> DELEGATE = new ThreadLocal<>();
public UserSession get() {
UserSession session = DELEGATE.get();
if (session != null) {
return session;
}
throw new UnauthorizedException("User is not authenticated");
}
public void set(UserSession session) {
DELEGATE.set(session);
}
public void incorrectCleanup() {
DELEGATE.set(null); // Noncompliant
}
// some other methods without a call to DELEGATE.remove()
}public class ThreadLocalUserSession implements UserSession {
private static final ThreadLocal<UserSession> DELEGATE = new ThreadLocal<>();
public UserSession get() {
UserSession session = DELEGATE.get();
if (session != null) {
return session;
}
throw new UnauthorizedException("User is not authenticated");
}
public void set(UserSession session) {
DELEGATE.set(session);
}
public void unload() {
DELEGATE.remove(); // Compliant
}
// ...
}From the same buckets as this rule.
All static JS/CSS/font/image files MUST use content-hashed filenames (e.g., app.9c1a7b.js) and be served with "Cache-Control: public, max-age=31536000, immutable". HTML and other non-fingerprinted documents MUST be served with "Cache-Control: no-cache" (or equivalent) to enable conditional revalidation.