Pretty print plugin performance issues

Pretty print plugin is slow, because:

• Calls flush method on every printed line.
• Use unbuffered output stream.

Combination of previous points results in poor performance. In my situation the plugin doubles the run time.

Single thread

When running Cucumber tests in a single thread, the bottleneck is in the OutputStreamWriter.flush() method.

Multi-threading

When running Cucumber tests in multiple threads, the bottleneck is still in the flush() method. Because printing is called from synchronised SynchronizedEventBus.send() method, a thread has to wait for flush() in other threads, which subsequently kills performance gains from multi-threaded solution.

Expected behaviour

Performance of the NiceAppendable class should be improved to be close to running tests without the plugin. A good idea may be not to flush on every line.

• Version: io.cucumber:cucumber-java:7.2.3
• Tests executed from IntelliJ IDEA 2021.3.2
• Build tool: Gradle 5.3.1
• OS: macOS Monterey 12.1

[mpkorstanje]

Very interesting. I’ll have to take a good look.

[mpkorstanje]

@vkuzel https://github.com/cucumber/cucumber-jvm/pull/2541 should be released in a few minutes. Would you mind giving it a try?