...

  --output-with-header Print out final results to output file with header. (default: false)
  --output-path OUTPUT-PATH Write final results to the file OUTPUT-PATH.

Proposed Changes

In ProducerPerformance:

parser.addArgument("--output-path")
        .action(store())
        .required(false)
        .type(String.class)
        .metavar("OUTPUT-PATH")
        .dest("outputPath")
        .help("Write final results (excluding metrics) to the file specified by OUTPUT-PATH.");

parser.addArgument("--output-with-header")
        .action(storeTrue())
        .required(false)
        .type(Boolean.class)
        .dest("outputWithHeader")
        .help("Print out final results to output file with headers.");

In ConsumerPerformance:

val outputWithHeaderOpt = parser.accepts("output-with-header", "Print out final results to output file with headers.")
val outputPathOpt = parser.accepts("output-path", "Write final results (excluding metrics) to the specified file.")
  .withOptionalArg()
  .describedAs("output file")
  .ofType(classOf[String])

Behavior:

• When "--output-path" is specified by user, final results of ProducerPerformance and ConsumerPerformance will be printed not only to the standard output but also to the given file in CSV format. An exception will be thrown if the file already exists.

...

• When "--output-with-header" is specified, a header record will be also printed into the output file (it will be the first line of the output). This argument only takes effect if  "--output-path" is also specified (documentation should).

Example:

Running the following ProducerPerformance ProducerPerformance tool with the following options:

bin/kafka-run-class.sh  org.apache.kafka.tools.ProducerPerformance --topic test --num-records 1000000 --throughput -1 --record-size  100 --producer-props bootstrap.servers=localhost:9092 --output-path  producer_stats.csv --output-with-header

will generate a an output file called producer_stats.csv file in CSV format: 

records sent,records/sec,MB/sec,ms avg latency,ms max latency,ms 50th,ms 95th,ms 99th,ms 99.9th
1000000,263713.0801687764,25.14963914573444,430.092296,873.0,490,801,870,873

without --output-with-header, only final results are printed

1000000,263713.0801687764,25.14963914573444,430.092296,873.0,490,801,870,873

Compatibility, Deprecation, And Migration Plan

There won't be any change of current behavior. New arguments of ProducerPerformance and ConsumerPerformance are optional. 

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