Testing / Karate Framework Interview questions
How does Karate handle parallel test execution using virtual threads?
Newer versions of Karate run on Java 21+ and use virtual threads, a lightweight concurrency mechanism introduced in modern Java, to execute large numbers of scenarios in parallel with far less overhead than traditional OS-backed thread pools require.
Karate testAll() { return Karate.run("classpath:tests") .tags("~@ignore") .parallel(200); }
Because virtual threads are much cheaper to create and schedule than traditional platform threads, a suite can run hundreds of scenarios concurrently without the manual thread-pool sizing and tuning that would otherwise be needed to avoid exhausting system resources; the runtime handles scheduling many lightweight virtual threads onto a much smaller number of actual OS threads automatically.
This is combined with Karate's own thread-safe JS engine (karate-js) underneath, since running scenarios concurrently is only actually safe if the JavaScript evaluation each scenario relies on can also run concurrently without interfering across threads.
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