Replace VLA with thread local vectors

src/connection.cpp

@@ -1,10 +1,14 @@
 #include "connection.hpp"
 #include "server.hpp" // Need this for releaseBackToServer implementation
+#include <climits>
 #include <cstdio>
 #include <cstdlib>
 #include <errno.h>
 #include <limits.h>
 
+// Static thread-local storage for iovec buffer
+static thread_local std::vector<struct iovec> g_iovec_buffer{IOV_MAX};
+
 Connection::Connection(struct sockaddr_storage addr, int fd, int64_t id,
                        size_t epoll_index, ConnectionHandler *handler,
                        Server &server)
@@ -62,8 +66,9 @@ int Connection::readBytes(char *buf, size_t buffer_size) {
 
 bool Connection::writeBytes() {
   while (!messages_.empty()) {
-    // Build iovec array up to IOV_MAX limit
-    struct iovec iov[IOV_MAX];
+    // Build iovec array up to IOV_MAX limit using thread-local vector
+    assert(g_iovec_buffer.size() == IOV_MAX);
+    struct iovec *iov = g_iovec_buffer.data();
     int iov_count = 0;
 
     for (auto it = messages_.begin();