Parallel execution is not working properly making one thread to wait for another to finish the action

[Shcherbakoval]

Description:
It looks like the parallel execution of Scenarios behaves more like a blocking queue, making one thread to wait for another to finish the action it doing at the moment. The action could anything like executing JS, Java code or making an HTTP call.

Steps to reproduce:
In the attached zip run the ExampleTest.java which is set to run a single Feature file containing 2 Scenarios both doing the same thing:

1. Print test name
2. Sleep for 2 seconds
3. Print wake up message

Actual result:
Both Scenarios are executed, one of them actually was sleeping for 2 seconds, another one however been sleeping for 4 seconds, thus waiting for the first Scenario to sleep and then start sleeping itself.

16:52:06.984 [pool-1-thread-1] INFO com.intuit.karate - Test 1 About to sleep for 2 seconds
16:52:06.984 [pool-1-thread-2] INFO com.intuit.karate - Test 2 About to sleep for 2 seconds
16:52:09.006 [pool-1-thread-1] INFO com.intuit.karate - Test 1 Woke up
16:52:11.010 [pool-1-thread-2] INFO com.intuit.karate - Test 2 Woke up

Expected result:
Both Scenarios should've slept for 2 seconds and not block each others execution. Producing the output like this, where difference between calls is actually 2 seconds

2022-12-19T16:49:33.850375 Thread-0 is about to sleep for 2 Seconds
2022-12-19T16:49:33.850422 Thread-1 is about to sleep for 2 Seconds
2022-12-19T16:49:35.874877 Thread-0 woke up after sleeping for 2 Seconds
2022-12-19T16:49:35.874139 Thread-1 woke up after sleeping for 2 Seconds

karateTest.zip

You can run this either from your favourite IDE or simply using mvn clean test.

[ptrthomas]

@Shcherbakoval this is good catch and thanks for this. but first let me correct you - the blocking only happens for JS code and not the other workloads (Java, normal HTTP calls). as proof try to run this test:

Feature: test sample feature

  Scenario: test1
    * karate.log("Test 1 About to sleep for 2 seconds")
    * java.lang.Thread.sleep(2000)
    * karate.log("Test 1 Woke up")

  Scenario: test2
    * karate.log("Test 2 About to sleep for 2 seconds")
    * java.lang.Thread.sleep(2000)
    * karate.log("Test 2 Woke up")

and you can look at the timeline report for confirmation:

So yes, we have this limitation that any JS code executed will perform a global lock. we don't like it - but there is a big history for this, refer: #2081

in my experience, and from what we hear from enterprise users, this is not an issue for normal tests as long as you ensure that any JS you use is only for utilities and business logic. if you use karate.callSingle() you can cache the results up-front and use it for all your tests.

@Shcherbakoval you are most welcome to contribute thoughts, ideas and ideally code to improve this ;) I will leave this open for a while for discussion, else close this as wontfix

[ptrthomas]

closing because of no response

[ptrthomas]

reopening as there is one more report of this: https://stackoverflow.com/q/75371624/143475

considering high priority. please try to build from source until we release 1.4.0.RC4: https://github.com/karatelabs/karate/wiki/Developer-Guide

[ptrthomas]

1.4.0 released