message: add large number of connections test
diff: #include "test_helpers.hpp"
  #include "duckdb/parser/parser.hpp"
  #include "duckdb/planner/logical_operator.hpp"
  +#include "duckdb/main/connection_manager.hpp"
  #include <chrono>
  #include <thread>
  @@ -500,3 +501,27 @@ TEST_CASE("Test opening an invalid database file", "[api]") {
  }
  REQUIRE(!success);
  }
  +
  +TEST_CASE("Test large number of connections to a single database", "[api]") {
  + auto db = make_unique<DuckDB>(nullptr);
  + auto &clientContext = ClientContext((*db).instance);
  + auto &connection_manager = ConnectionManager::Get(clientContext);
  +
  + vector<unique_ptr<Connection>> connections;
  + int numCon = 5000;
  +
  + for (size_t i = 0; i < numCon; i++) {
  + auto conn = make_unique<Connection>(*db);
  + connections.push_back(move(conn));
  + }
  +
  + REQUIRE(connection_manager.connections.size() == numCon);
  +
  + for (size_t i = 0; i < connections.size(); i++) {
  + auto conn = *connections[i];
  + connections.erase(connections.begin() + i);
  + i--;
  + }
  +
  + REQUIRE(connection_manager.connections.size() == 0);
  +}
  