Make the default for epoll_instances io_threads/2

src/config.cpp

@@ -84,7 +84,16 @@ void ConfigParser::parse_server_config(const auto &toml_data,
     parse_field(srv, "unix_socket_path", config.unix_socket_path);
     parse_field(srv, "max_request_size_bytes", config.max_request_size_bytes);
     parse_field(srv, "io_threads", config.io_threads);
+
+    // Set epoll_instances default to io_threads/2 (min 1) if not explicitly
+    // configured
+    bool epoll_instances_specified = srv.contains("epoll_instances");
+    if (!epoll_instances_specified) {
+      config.epoll_instances = std::max(1, config.io_threads / 2);
+    } else {
       parse_field(srv, "epoll_instances", config.epoll_instances);
+    }
+
     parse_field(srv, "event_batch_size", config.event_batch_size);
     parse_field(srv, "max_connections", config.max_connections);
     parse_field(srv, "read_buffer_size", config.read_buffer_size);

src/config.hpp

@@ -20,8 +20,8 @@ struct ServerConfig {
   size_t max_request_size_bytes = 1024 * 1024;
   /// Number of I/O threads for handling connections and network events
   int io_threads = 1;
-  /// Number of epoll instances to reduce epoll_ctl contention (default: 2, max:
-  /// io_threads)
+  /// Number of epoll instances to reduce epoll_ctl contention (default:
+  /// io_threads/2, max: io_threads)
   int epoll_instances = 2;
   /// Event batch size for epoll processing
   int event_batch_size = 32;

test_config.toml

@@ -7,10 +7,9 @@ port = 8080
 # Maximum request size in bytes (for 413 Content Too Large responses)
 max_request_size_bytes = 1048576  # 1MB
 # Number of I/O threads for handling connections and network events
-io_threads = 6
+io_threads = 12
 # Event batch size for epoll processing
 event_batch_size = 32
-epoll_instances = 2
 
 [commit]
 # Minimum length for request_id to ensure sufficient entropy