One of the programs I wrote before has been tested on one machine and has not been tested on another. I can’t figure out why. At first I thought it was a computer problem, but later I found that it would not appear in the place where the network is good, and the place where the network is bad is often seen. At the time of double code is found written in the Update, a StartCoroutine invoke the WWW class, every call Update will open a thread calls the WWW, under the condition of network good WWW can be returned in time, there will not be Too Many threads, once the network condition is bad, this way has been pulling thread, there waiting for the thread to return again, leading to excess thread, appear “Too Many threads”, I used the solution is put WWW calls in a while (true), Each call to WWW must wait for the last WWW return.