Parallel execution on testng

Question

I am new at parallel automated testing. I am using testng to run my tests in parallel. The problem is that I am using data providers to provide the data to my tests. I have put the attribute parallel = true on my data providers. When I run the tests, eight threads are created. After a few tests the thread is closed and a new one is created. I installed allure to generate a report about the results of my tests. This is the timeline:Image.

Is there any configuration that let me modify this behavior? I don't want the threads to close by themselves. The behavior I am looking for is that the thread doesn't close itself after a few tests and then a new one is created. I want to run all tests on the 8 threads that are created at the beginning of the run.

I tried this suite that I made for this class but it doesn't work like I was thinking

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE suite SYSTEM "http://testng.org/testng-1.0.dtd" >

<suite name="suite" parallel="methods" data-provider-thread-count="8" thread-count="1">
    <groups>
        <run>
            <include name="testgroup"></include>
        </run>
    </groups>
    <test name="test">
        <classes>
            <class name="test1"/>
        </classes>
    </test>
</suite>

Thanks