JDK-8210280 - Unnecessary reallocation when invoking HashMap.putAll()

Michal Vala mvala at redhat.com
Wed Dec 19 17:32:30 UTC 2018

On 12/19/18 4:15 PM, Martin Buchholz wrote:
> On Wed, Dec 19, 2018 at 6:59 AM Roger Riggs <Roger.Riggs at oracle.com> wrote:
>> Hi Martin,
>> It is also useful and conventional to print the seed of the random
>> so that if necessary it can be reproduced.
> For many years, we've been using ThreadLocalRandom for testing, and that
> does not allow setting a seed.
> I remain unconvinced that saving a seed has value in the real world.  When
> a randomized test fails, running it with sufficient iterations has always
> worked for me.

What's the reason behind using ThreadLocalRandom?

In my opinion, reproducing the issue is key. One failure of randomized test run 
might be caused by one issue, second run due to another issue. How we reproduce 
then and how we know even how many issues we have? When we're running random 
tests until it pass, it might even hide the issue.

They sure have good value on reveal the issue, but then we have to know how to 
reproduce and what we're searching for.

If this case would not require ThreadLocalRandom and Random is enough, I'd like 
to use that because of benefits I've mentioned.

Michal Vala
Red Hat Czech

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