best practices for 'Too many open files' scenarios in a Java NIO server application?
I've looked through the documentation and I'm still confused about I'm relatively new to this, so bear with me. I'm running a Java NIO server application using Java 11 that handles multiple client connections, but I keep working with a `java.nio.channels.AlreadyBoundException` followed by a `Too many open files` behavior. This behavior appears when I start to reach around 500 concurrent connections, and I suspect it's linked to the file descriptors limit on my operating system. I've tried increasing the maximum number of open files using the command `ulimit -n 1024`, but it doesn't seem to have an effect on my application. I also used `lsof -p <PID>` to check the number of open file descriptors, and it shows that my application is indeed hitting the limit. Here's a simplified version of my server code: ```java import java.io.IOException; import java.net.InetSocketAddress; import java.nio.ByteBuffer; import java.nio.channels.ServerSocketChannel; import java.nio.channels.SocketChannel; import java.nio.channels.Selector; import java.util.Iterator; public class NioServer { public static void main(String[] args) throws IOException { Selector selector = Selector.open(); ServerSocketChannel serverSocketChannel = ServerSocketChannel.open(); serverSocketChannel.bind(new InetSocketAddress(8080)); serverSocketChannel.configureBlocking(false); serverSocketChannel.register(selector, serverSocketChannel.validOps()); while (true) { selector.select(); Iterator<java.nio.channels.SelectionKey> keys = selector.selectedKeys().iterator(); while (keys.hasNext()) { java.nio.channels.SelectionKey key = keys.next(); if (key.isAcceptable()) { SocketChannel client = serverSocketChannel.accept(); client.configureBlocking(false); client.register(selector, client.validOps()); } else if (key.isReadable()) { ByteBuffer buffer = ByteBuffer.allocate(256); SocketChannel client = (SocketChannel) key.channel(); client.read(buffer); // process data } keys.remove(); } } } } ``` In addition, I've confirmed that my socket options are set correctly. The question seems to stem from the way connections are managed in NIO as they don't close properly under high load. I've looked into using a connection pool or adjusting the backlog size on the server socket, but I'm unsure how to implement that effectively in an NIO context. Has anyone faced this scenario and found a reliable solution for managing high numbers of concurrent connections without hitting the file descriptor limit? My development environment is macOS. I'd really appreciate any guidance on this. How would you solve this?