On Mon, 30 Mar 2026 14:45:06 GMT, Aleksey Shipilev <[email protected]> wrote:
>> Andrew Haley has updated the pull request incrementally with one additional
>> commit since the last revision:
>>
>> Fix up any out-of-range offsets
>
> src/hotspot/share/runtime/javaThread.cpp line 546:
>
>> 544: do {
>> 545: state = os::random();
>> 546: } while (state == 0);
>
> Curious: why should not the initial state be zero?
When we're using CRC (i.e. a linear-feedback shift register) to generate random
data, each step shifts the current state left by n bits then takes the
remainder modulo some big binary polynomial. This is great unless you start
with zero, in which case all results are zero. The alternative is to add a
small constant every time, but unless that constant is carefully chosen you can
get short cycles. Better to start with nonzero.
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PR Review Comment: https://git.openjdk.org/jdk/pull/28541#discussion_r3010901379
