The web client currently does not support to configure the parallelism. There is an issue for it. So it will soon be fixed.
--- What you can do right now: 1) Either configure the following key in flink-conf.yaml parallelism.default: PARALLELISM 2) Or set it via the environment: final ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment(); env.setParallelism(PARALLELISM); You could parse the parallelism via args. --- If you use the Flink CLI via bin/flink you don't have to do any of this, but can do the following: bin/flink run -p PARALLELISM xyz.jar This will set the default parallelism for the job for you. This feature is coming up for the web client. – Ufuk
