👀 Views: 0 💬 Answers: 1 📅 Created: 2025-09-09

Java multithreading CSV parsing

I'm having a hard time understanding I'm relatively new to this, so bear with me. I'm attempting to set up Building an application that processes large CSV files for data ingestion, I've stumbled across challenges while refactoring legacy code. The existing implementation reads the entire file into memory, which is inefficient for our growing data volume. To improve scalability, I’m trying to implement a multi-threaded approach where each thread handles a portion of the file. After some research, I began using Java's `ForkJoinPool` but faced issues with proper synchronization when writing to a shared data structure. Here’s a simplified version of my current setup: ```java import java.io.*; import java.util.*; import java.util.concurrent.*; public class CSVParser { private static final int THREAD_COUNT = 4; private List<List<String>> data = Collections.synchronizedList(new ArrayList<>()); public void parseCSV(File file) throws IOException, InterruptedException, ExecutionException { ForkJoinPool pool = new ForkJoinPool(THREAD_COUNT); try (BufferedReader br = new BufferedReader(new FileReader(file))) { String line; List<Future<?>> futures = new ArrayList<>(); while ((line = br.readLine()) != null) { futures.add(pool.submit(() -> data.add(Arrays.asList(line.split(",")))); } for (Future<?> future : futures) { future.get(); // Ensure all tasks are completed } } } } ``` Although this approach seems promising, I ran into a concurrency issue, where sometimes the data ends up being corrupted or incomplete, particularly when dealing with malformed CSV lines. I've tried using `BlockingQueue` to handle synchronization but still find myself wrestling with edge cases. Additionally, I’m uncertain how to best manage the line parsing to ensure that lines are handled atomically without losing performance. Any insights or best practices on refining this multi-threaded CSV parsing strategy would be greatly appreciated. Also, suggestions for handling malformed entries gracefully would be a bonus. My development environment is Windows 11. What am I doing wrong? This is for a mobile app running on Linux. Any pointers in the right direction? This is for a application running on Ubuntu 22.04.