use-global-thread-pool works incorrectly: threads count depends on count of DDT in code

[kool79]

When use-global-thread-pool == "true":

1. I cannot limit thread count to X if my code has X data-driven tests. I have a class with 5 DDT. Suite has the next settings:

<suite name="Suite" parallel="methods" thread-count="5" data-provider-thread-count="3"
       use-global-thread-pool="true"
>

When I try to start the suite, suddenly it is blocked --
[Deadlock condition detected] Cannot run 5 data driven tests on just 5 threads when using common thread pool. Please increase the number of threads to at-least 6.

• Even if I never use those tests (filter them) -- I cannot start the suite.
• Whan I had 4 DDT tests in our codebase, and someone adds one additional DDT test -- our suite stopped execution on CI on a current infrastructure, which can handle max 5 threads. It is very ugly. Why our codebase (our tests) should depend on infrastructure? Why execution is stopped even if we dont run those tests? (filtered from execution with a listeners)

2. My suite have a class with a 5 DDTs, each have a 8 data-rows (total 5*40 = cases). When I set a bigger number of thread-count:

<suite name="Suite" parallel="methods" thread-count="6" data-provider-thread-count="3"
       use-global-thread-pool="true"
>

I expect that all threads will be used for execution. Instead, I see that tests are executed in 1 thread! When I increase number of thread-count to 7, tests are invoked with 2 threads only (screenshot below) . So the actual thread count is equals to - N where N -- count of DDT in my code! So, when I push additional test onto my repo, I have degraded performance, because of lower threads

DataProviderParallelTest.java

testng-shared-pool.xml

pom.xml