In current StreamLoad design, FE will recive load information from BE by RPC call, but I found that if the coordinator BE down when doing stream load fragment, FE will not receive any rollback txn call and the txns on the coordinator BE will never finished and the state is always PREPARE, it is because FE has no idea that the txn will aborted finally cause the fragment execute failed, and be cann't notify FE that case. So, if user set a long timeout stream load in parameters, there are a lots txns in GlobalTxnMgr, and they occupied the txn queue sizes and memory usage in FE, it may block the stream load.So, I define a callback function to cancel all txn which coordiator BE is down to solve this problem