[Bug] ThreadContext Leak in Log4j2Demo causing Thread Pollution

[QiuYucheng2003]

Description

The Log4j2Demo.java class demonstrates unsafe usage of ThreadContext within a thread pool environment.

The Bug

In the createTask method (Line 38), ThreadContext.put("task", ...) is invoked inside a Runnable. However, there is no corresponding ThreadContext.remove("task") or clearMap() call at the end of the execution.

Impact

When the thread returns to the ExecutorService pool, it remains "dirty" with the task context value. Subsequent tasks reusing this thread will inherit this stale context data, leading to Log Context Pollution (incorrect data appearing in unrelated logs).

Location

File: Log4j2Demo.java
Method: createTask() -> run()
Line: 43 (Missing cleanup after put)

Proposed Fix

Wrap the business logic in a try...finally block to ensure context cleanup:

public void run() {
    ThreadContext.put("task", new Date().toString());
    try {
        logger.info("Log in Runnable!");
    } finally {
        ThreadContext.remove("task"); // Preventing leak
    }
}