[FLINK-2249] ExecutionEnvironment: Ignore calls to execute() if no data sinks defined

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Won't Fix
• Affects Version/s: 0.9
• Component/s: API / Scala
• Assignee: Chesnay Schepler
• Reporter: Maximilian Michels
• Created: 19/Jun/15 12:13
• Updated: 28/Feb/19 14:29
• Resolved: 19/Nov/15 10:05

Description

The basic skeleton of a Flink program looks like this:

ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();

// bootstrap DataSet
DataSet<..> ds = env.fromElements(1,2,3,4);
// perform transformations
..
// define sinks, e.g.
ds.writeToTextFile("/some/path");
// execute
env.execute()

First thing users do is to change ds.writeToTextFile("/some/path"); into ds.print();. But that fails with an Exception ("No new data sinks defined...").

In FLINK-2026 we made this exception message easier to understand. However, users still don't understand what is happening. Especially because they see Flink executing and then failing.

I propose to ignore calls to execute() when no sinks are defined. Instead, we should just print a warning: "Detected call to execute without any data sinks. Not executing."

Issue Links

• is related to: FLINK-2026 Error message in count() only jobs