On Mon, 27 Mar 2023 16:18:22 GMT, Sergey Tsypanov <stsypa...@openjdk.org> wrote:
>> By default `BufferedInputStream` is constructed with internal buffer with
>> capacity 8192. In some cases this buffer is never used, e.g. when we call
>> `IS.readNBytes()` or `IS.readAllBytes()` (relying on `BIS.read1()`) or when
>> `BufferedInputStream` is cascaded.
>
> Sergey Tsypanov has updated the pull request incrementally with one
> additional commit since the last revision:
>
> 8304745: Add comments for benchmark
Marked as reviewed by jpai (Reviewer).
src/java.base/share/classes/java/io/BufferedInputStream.java line 181:
> 179: byte[] buffer = buf;
> 180: if (allocateIfEmpty && buffer == EMPTY) {
> 181: buffer = new byte[initialSize];
It took me a few rounds of reading this code to realize that this array
allocation will only be done once even when multiple threads are involved,
because when `buffer == EMPTY` (i.e. `BufferedInputStream` is not subclassed),
then the call to `getBufIfOpen(...)` always happens after acquiring the `lock`.
So, only one thread will ever enter this block. Looks good to me.
-------------
PR Review: https://git.openjdk.org/jdk/pull/13150#pullrequestreview-1372264626
PR Review Comment: https://git.openjdk.org/jdk/pull/13150#discussion_r1158097110
