Hi, Flink program should have at least one data sink. When your program calls `print` method, the method adds a data sink into your program automatically and execute it immediately. If you want to run Flink program without calling `print` method, you should add a data sink into your program and execute it manually by calling `execute` method of `ExecutionEnvironment` object.
Note that only some methods about data sink such as `print`, `count` and `collect` execute the program immediately. There are more detail descriptions about data sink [1] and lazy evaluation [2] in Flink documentation. The documentation will help you to understand the structure of Flink program. Regards, Chiwan Park [1] https://ci.apache.org/projects/flink/flink-docs-release-0.9/apis/programming_guide.html#data-sinks [2] https://ci.apache.org/projects/flink/flink-docs-release-0.9/apis/programming_guide.html#lazy-evaluation > On Jul 20, 2015, at 2:59 AM, Madabhattula Rajesh Kumar <mrajaf...@gmail.com> > wrote: > > Hi Scahin, > > Thank you for the response. I have commented counts print line. After that I > got below exception > > Exception in thread "main" java.lang.RuntimeException: No data sinks have > been created yet. A program needs at least one sink that consumes data. > Examples are writing the data set or printing it. > at > org.apache.flink.api.java.ExecutionEnvironment.createProgramPlan(ExecutionEnvironment.java:914) > at > org.apache.flink.api.java.ExecutionEnvironment.createProgramPlan(ExecutionEnvironment.java:893) > at > org.apache.flink.api.java.LocalEnvironment.execute(LocalEnvironment.java:50) > at > org.apache.flink.api.scala.ExecutionEnvironment.execute(ExecutionEnvironment.scala:590) > at WordCount$.main(WordCount.scala:13) > at WordCount.main(WordCount.scala) > > Regards, > Rajesh > > On Sun, Jul 19, 2015 at 8:26 PM, Sachin Goel <sachingoel0...@gmail.com> wrote: > Hi > You do not need to call env.execute after doing a print call. Print itself > triggers the execution. The reason for the Exception is quite obvious. After > the print call, there is no sink for the program execution. So, execution > cannot proceed. > You can however explicitly define a sink and then call env.execute. > > Cheers! > Sachin > > -- Sachin Goel > Computer Science, IIT Delhi > m. +91-9871457685 > > On Sun, Jul 19, 2015 at 8:06 PM, Madabhattula Rajesh Kumar > <mrajaf...@gmail.com> wrote: > Hi, > > I have written simple wordcount program in scala. When I execute the program, > I'm getting below exception. > > Please let me know how to fix this issue. I'm using Flink 0.9.0 version > > Below is the program :- > > val env = ExecutionEnvironment.getExecutionEnvironment > // get input data > val text = env readTextFile("/Users/hadoop2/Data/word.txt") > val counts = text flatMap(l=>l split(" ")) map(word=>(word,1)) groupBy(0) > sum(1) > // emit result > counts print > env.execute("TEST") > > Exception :- > > Exception in thread "main" java.lang.RuntimeException: No new data sinks have > been defined since the last execution. The last execution refers to the > latest call to 'execute()', 'count()', 'collect()', or 'print()'. > at > org.apache.flink.api.java.ExecutionEnvironment.createProgramPlan(ExecutionEnvironment.java:910) > at > org.apache.flink.api.java.ExecutionEnvironment.createProgramPlan(ExecutionEnvironment.java:893) > at > org.apache.flink.api.java.LocalEnvironment.execute(LocalEnvironment.java:50) > at > org.apache.flink.api.scala.ExecutionEnvironment.execute(ExecutionEnvironment.scala:590) > at WordCount$.main(WordCount.scala:17) > at WordCount.main(WordCount.scala) > > Regards, > Rajesh > >
