All Thread Groups do not start at the same time

**indravardhan** ([Bug 58182](https://bz.apache.org/bugzilla//show_bug.cgi?id=58182&redirect=false)):
We have a test plan that has multiple threads groups. Each thread group has same value for ramp up period and test duration(using variables).
Startup delay is provided as 0.

When test starts we notice that all threads groups are started sequentially and this leads to test running for longer duration then expected.
As group which was started late will finish later.

Below is one example.

~> grep "Starting thread group number” *
2015/07/22 03:51:45 INFO - jmeter.threads.ThreadGroup: Starting thread group number 1 threads 31 ramp-up 300 perThread 9677.419 delayedStart=false
2015/07/22 03:52:34 INFO - jmeter.threads.ThreadGroup: Starting thread group number 2 threads 11 ramp-up 300 perThread 27272.727 delayedStart=false
2015/07/22 03:52:50 INFO - jmeter.threads.ThreadGroup: Starting thread group number 3 threads 5 ramp-up 300 perThread 60000.0 delayedStart=false
2015/07/22 03:52:58 INFO - jmeter.threads.ThreadGroup: Starting thread group number 4 threads 2 ramp-up 300 perThread 150000.0 delayedStart=false
2015/07/22 03:53:01 INFO - jmeter.threads.ThreadGroup: Starting thread group number 5 threads 13 ramp-up 300 perThread 23076.924 delayedStart=false
2015/07/22 03:53:20 INFO - jmeter.threads.ThreadGroup: Starting thread group number 6 threads 7 ramp-up 300 perThread 42857.145 delayedStart=false
2015/07/22 03:53:31 INFO - jmeter.threads.ThreadGroup: Starting thread group number 7 threads 5 ramp-up 300 perThread 60000.0 delayedStart=false
2015/07/22 03:53:39 INFO - jmeter.threads.ThreadGroup: Starting thread group number 8 threads 3 ramp-up 300 perThread 100000.0 delayedStart=false
2015/07/22 03:53:44 INFO - jmeter.threads.ThreadGroup: Starting thread group number 9 threads 4 ramp-up 300 perThread 75000.0 delayedStart=false

Below is code snippet from org.apache.jmeter.engine.StandardJMeterEngine#run().

while (running && iter.hasNext()) {// for each thread group
AbstractThreadGroup group = iter.next();
.
.
log.info("Starting ThreadGroup: " + groupCount + " : " + groupName);
startThreadGroup(group, groupCount, searcher, testLevelElements, notifier);
.
.
}

org.apache.jmeter.engine.StandardJMeterEngine#startThreadGroup().
private void startThreadGroup(AbstractThreadGroup group, int groupCount, SearchByClass<?> searcher, List<?> testLevelElements, ListenerNotifier notifier)
{
.
.
group.start(groupCount, notifier, threadGroupTree, this);
}

and ThreadGroup.start() method will spawn all threads for a group. So second group will start once threads are created for first group.

Now one solution I have found is to enable “Delay thread creation until needed” and set startup delay to some value > 0.
This will run new ThreadStarter thread for each group and all groups will start at the same time.

Can we have some option to enable parallel start of all thread groups ?

Votes in Bugzilla: 1
OS: All

Depends on:
* https://github.com/apache/jmeter/issues/3638