spark context exit abnormally

I recently met a problem on Spark.I create a sparkcontext instance with yarn-client mode in my program (a web application) for users to submit their jobs ,It can work for a for a period of time, but then it suddenly comes out without any new job running.It looks like the context has been killed, and I'm not sure whether the problem is on the yarn or on the spark.zou can see my screenshot and log file.