I remember having similar problems with green threads as they were called back before they were removed from the language. (https://en.m.wikipedia.org/wiki/Gree

I remember having similar problems with green threads as they were called back before they were removed from the language. (https://en.m.wikipedia.org/wiki/Green_thread https://en.m.wikipedia.org/wiki/Green_thread) In our case, it was because of developer failed to use a finely block to close the socket on our side.