RFR 8081027: Create a common test to check adequacy of initial size of static HashMap/ArrayList fields

Ivan Gerasimov ivan.gerasimov at oracle.com
Fri May 29 16:42:48 UTC 2015

Thank you Martin for review!

On 29.05.2015 3:03, Martin Buchholz wrote:
> Approved.
> On Thu, May 28, 2015 at 3:43 PM, Ivan Gerasimov 
> <ivan.gerasimov at oracle.com <mailto:ivan.gerasimov at oracle.com>> wrote:
>     Good naming is one of the most difficult part of coding IMO.
>     The chosen names were meant to be read literally: "optimal
>     capacity of ArrayList", etc.
>     I agree, 'assert' would tell more about these methods' intention,
>     but I'm not sure how to include it in the names.
>     Maybe rename the class to AssertOptimalCapacity?
> Assertions are a class of names we are used to importing statically. 
> Junit and Testng both have collections of static methods named assertXXX.
>>     For ArrayLists, I would have been happy enough just testing that
>>     we have 100% utilization, i.e. size of array is the same as size
>>     of the List, without checking the initial capacity.
>     But then the test wouldn't have caught the "bug" in
>     src/java.base/share/classes/sun/security/ssl/ExtensionType.java
>     The ArrayList was pre-sized to 9, and after reallocation the
>     capacity happened to become (9 + 9/2) = 13, which by coincidence
>     is the final size of the List.
> It's a tradeoff of maintenance burden vs performance. Note also that 
> oversize is a much bigger performance bug than undersize because you 
> pay for it for the entire process, not just startup.

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