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Example showing failure when re-using an OutputTag in multiple ProcessFunctions
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| import argparse | |
| import logging | |
| import sys | |
| from pyflink.common import WatermarkStrategy, Encoder, Types | |
| from pyflink.datastream import StreamExecutionEnvironment, RuntimeExecutionMode, ProcessFunction, OutputTag | |
| from pyflink.datastream.connectors.file_system import FileSource, StreamFormat, FileSink, OutputFileConfig, RollingPolicy | |
| word_count_data = ["To be, or not to be,--that is the question:--", | |
| "Whether 'tis nobler in the mind to suffer", | |
| "The slings and arrows of outrageous fortune", | |
| "Or to take arms against a sea of troubles,", | |
| "And by opposing end them?--To die,--to sleep,--", | |
| "No more; and by a sleep to say we end", | |
| "The heartache, and the thousand natural shocks", | |
| "That flesh is heir to,--'tis a consummation", | |
| "Devoutly to be wish'd. To die,--to sleep;--", | |
| "To sleep! perchance to dream:--ay, there's the rub;", | |
| "For in that sleep of death what dreams may come,", | |
| "When we have shuffled off this mortal coil,", | |
| "Must give us pause: there's the respect", | |
| "That makes calamity of so long life;", | |
| "For who would bear the whips and scorns of time,", | |
| "The oppressor's wrong, the proud man's contumely,", | |
| "The pangs of despis'd love, the law's delay,", | |
| "The insolence of office, and the spurns", | |
| "That patient merit of the unworthy takes,", | |
| "When he himself might his quietus make", | |
| "With a bare bodkin? who would these fardels bear,", | |
| "To grunt and sweat under a weary life,", | |
| "But that the dread of something after death,--", | |
| "The undiscover'd country, from whose bourn", | |
| "No traveller returns,--puzzles the will,", | |
| "And makes us rather bear those ills we have", | |
| "Than fly to others that we know not of?", | |
| "Thus conscience does make cowards of us all;", | |
| "And thus the native hue of resolution", | |
| "Is sicklied o'er with the pale cast of thought;", | |
| "And enterprises of great pith and moment,", | |
| "With this regard, their currents turn awry,", | |
| "And lose the name of action.--Soft you now!", | |
| "The fair Ophelia!--Nymph, in thy orisons", | |
| "Be all my sins remember'd."] | |
| output_tag1 = OutputTag("side-output1", Types.STRING()) | |
| output_tag2 = OutputTag("side-output2", Types.STRING()) | |
| class LinesWithTheToSideOutput(ProcessFunction): | |
| """ | |
| Any line that starts with "The" will be emitted to output_tag side output. | |
| """ | |
| def process_element(self, line: str, ctx: ProcessFunction.Context): | |
| if line.startswith("The"): | |
| yield output_tag1, "sideout-line-the: " + line | |
| else: | |
| # emit data to regular output | |
| yield line | |
| class LinesWithAndToSideOutput(ProcessFunction): | |
| """ | |
| Any line that starts with "And" will be emitted to output_tag side output. | |
| """ | |
| def process_element(self, line: str, ctx: ProcessFunction.Context): | |
| if line.startswith("And"): | |
| # Reusing output_tag1. | |
| # If we use output_tag2 (here and in the get_side_output call below), this work fine. | |
| yield output_tag1, "sideout-line-and: " + line | |
| else: | |
| # emit data to regular output | |
| yield line | |
| def word_count(input_path, output_path): | |
| env = StreamExecutionEnvironment.get_execution_environment() | |
| env.set_runtime_mode(RuntimeExecutionMode.BATCH) | |
| # write all the data to one file | |
| env.set_parallelism(1) | |
| # define the source | |
| if input_path is not None: | |
| ds = env.from_source( | |
| source=FileSource.for_record_stream_format(StreamFormat.text_line_format(), | |
| input_path) | |
| .process_static_file_set().build(), | |
| watermark_strategy=WatermarkStrategy.for_monotonous_timestamps(), | |
| source_name="file_source" | |
| ) | |
| else: | |
| print("Executing word_count example with default input data set.") | |
| print("Use --input to specify file input.") | |
| ds = env.from_collection(word_count_data) | |
| def split(line): | |
| yield from line.split() | |
| #### EXAMPLE FAILURE HERE | |
| processed_ds1 = ds.process(LinesWithTheToSideOutput()) | |
| side_output_ds1 = processed_ds1.get_side_output(output_tag1) | |
| # This process call fails, I think because output_tag1 is already used in LinesWithTheToSideOutput() | |
| # TypeError: cannot pickle '_thread.RLock' object | |
| processed_ds2 = processed_ds1.process(LinesWithAndToSideOutput()) | |
| side_output_ds2 = processed_ds2.get_side_output(output_tag1) | |
| #### END EXAMPLE FAILURE | |
| # compute word count | |
| ds = processed_ds2.flat_map(split) \ | |
| .map(lambda i: (i, 1), output_type=Types.TUPLE([Types.STRING(), Types.INT()])) \ | |
| .key_by(lambda i: i[0]) \ | |
| .reduce(lambda i, j: (i[0], i[1] + j[1])) | |
| # define the sink | |
| if output_path is not None: | |
| ds.sink_to( | |
| sink=FileSink.for_row_format( | |
| base_path=output_path, | |
| encoder=Encoder.simple_string_encoder()) | |
| .with_output_file_config( | |
| OutputFileConfig.builder() | |
| .with_part_prefix("prefix") | |
| .with_part_suffix(".ext") | |
| .build()) | |
| .with_rolling_policy(RollingPolicy.default_rolling_policy()) | |
| .build() | |
| ) | |
| else: | |
| print("Printing result to stdout. Use --output to specify output path.") | |
| ds.print() | |
| if side_output_ds1: | |
| side_output_ds1.print() | |
| if side_output_ds1: | |
| side_output_ds2.print() | |
| # submit for execution | |
| env.execute() | |
| if __name__ == '__main__': | |
| logging.basicConfig(stream=sys.stdout, level=logging.INFO, format="%(message)s") | |
| parser = argparse.ArgumentParser() | |
| parser.add_argument( | |
| '--input', | |
| dest='input', | |
| required=False, | |
| help='Input file to process.') | |
| parser.add_argument( | |
| '--output', | |
| dest='output', | |
| required=False, | |
| help='Output file to write results to.') | |
| argv = sys.argv[1:] | |
| known_args, _ = parser.parse_known_args(argv) | |
| word_count(known_args.input, known_args.output) |
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