On Tue, 28 Feb 2023 07:43:13 GMT, Tagir F. Valeev <tval...@openjdk.org> wrote:
>> Jim Laskey has updated the pull request incrementally with one additional
>> commit since the last revision:
>>
>> Optimize for empty CharSequence
>
> src/java.base/share/classes/java/lang/AbstractStringBuilder.java line 1903:
>
>> 1901: throw new OutOfMemoryError("Required length exceeds
>> implementation limit");
>> 1902: }
>> 1903: int total = count * length;
>
> We may avoid division if we use the long type:
>
>
> long totalLong = ((long) count) * length;
> if (totalLong > Integer.MAX_VALUE - offset) {
> throw new OutOfMemoryError("Required length exceeds implementation
> limit");
> }
> int total = (int) totalLong;
>
>
> Should be faster.
I'm a bit surprised this (and the original code) is throwing `OutOfMemoryError`
when running into the max array size. It is not truly an out of memory error,
but being an `Error`, it would evade standard catch `Exception` blocks. I
would think this is more of an `IllegalStateException` or perhaps something
array specific.
`OutOfMemoryError` is documented pretty specifically that an object allocation
failed after exhaustive GC, but no allocation or GC happened:
>Thrown when the Java Virtual Machine cannot allocate an object because it is
>out of memory, and no more memory could be made available by the garbage
>collector.
... which is not happening here at all. This leads me to believe the error is
not used correctly here.
Other reasons I find it surprising: `StringBuilder` is not documented to throw
this anywhere, it seems to just leak through from various methods implemented
by `AbstractStringBuilder`.
-------------
PR: https://git.openjdk.org/jdk/pull/12728
