RFR 8218227 : StringBuilder constructor throws confusing NegativeArraySizeException

[Ivan Gerasimov]

Thank you Roger for reviewing!


On 2/4/19 11:32 AM, Roger Riggs wrote:
> Hi Ivan,
>
> A good boundary condition to clean up.
>
> Should tests for StringBuffer be added too?
>
Yes, let's add them.

Please find the updated webrev here:
http://cr.openjdk.java.net/~igerasim/8218227/01/webrev/

With kind regards,
Ivan

> Maxing out the length at MAX_VALUE must always result in an OOM.
> If such an allocation were to succeed, it would violate the specified 
> initial capacity requirement.
>
> Thanks, Roger
>
>
> On 02/02/2019 02:28 AM, Ivan Gerasimov wrote:
>> Hello!
>>
>> The spec of the constructors 
>> StringBuilder(String)/StringBuilder(CharSequence) states that the 
>> initial capacity of the builder will be set to the length of the 
>> argument plus 16.
>> This causes them to throw confusing NegativeArraySizeException when 
>> the argument's length is close to Integer.MAX_VALUE.
>>
>> Let the arguments length be (Integer.MAX_VALUE - DELTA), like in the 
>> code below:
>>
>>         String str = "Z".repeat(Integer.MAX_VALUE - DELTA);
>>         StringBuilder sb = new StringBuilder(str);
>>
>> Currently the behavior is as following:
>>     0 <= DELTA <= 2 - unable to construct str,
>>     2 <= DELTA <= 15 - NegativeArraySizeException is thrown,
>>     16 <= DELTA <= 17 - OutOfMemoryError is thrown,
>>     DELTA >= 18 - works fine.
>>
>> With the fix, OOM will be thrown for all DELTA <= 17.
>>
>> Also the fix will make constructing a StringBuilder from UTF16 coded 
>> String slightly more efficient.
>>
>> BUGURL: https://bugs.openjdk.java.net/browse/JDK-8218227
>> WEBREV: http://cr.openjdk.java.net/~igerasim/8218227/00/webrev/
>>
>> Would you please help review the fix?
>>
>
>

-- 
With kind regards,
Ivan Gerasimov