The subject matter of futures trading is a standard contract, which must be completed by both parties. There is no buyer, only the seller, and it is impossible to successfully trade. Therefore, in the futures market, there are many empty orders and many corresponding orders for a certain variety. There can't be more or less.

When both long and short funds are infinite and trading is active, the "total" short position of stock futures can be infinite. But for institutional or personal accounts, it is impossible to hold empty orders or multiple orders indefinitely. The futures market has a position limit system to prevent people from manipulating the market.