multithreading Windows Service hangs SqlServerService

Question

i create a windiows service which fetch data from sql server and then create a request , sends request to API endpoint which responds in one minute (pretty slow )and on successful i update records status to complete or failed  around i use multithreading to interact with database (sqlserver) . the problem is my service stops working i dont know why it hangs SqlServer Service  . when i stop sqlserver Service  and restart then my service continuing fetch data and on successful response i update records status to complete . 

 

appreciate for any help