RFR: JDK-8243991 Use standard -Xss argument in java command line

[Magnus Ihse Bursie]

On 2020-04-28 12:17, David Holmes wrote:
> Hi Magnus,
>
> On 28/04/2020 7:42 pm, Magnus Ihse Bursie wrote:
>> We should use the official -Xss argument[1] in command lines, instead 
>> of the non-standard -XX:ThreadStackSize.
>>
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8243991
>> WebRev: 
>> http://cr.openjdk.java.net/~ihse/JDK-8243991-fix-Xss-in-java-args/webrev.01
>
> This isn't right. ThreadStackSize takes a value in KB, whereas -Xss is 
> a value in bytes. You won't be able to even start the VM with the 
> values you have specified.
Hm, I need to double-check that. I've extracted this as a separate fix 
for another bug I've been working on, since it was mostly unrelated to 
that fix, but I had no issues starting the VM.

I fail to understand, though, why we use this peculiar value for the 
stack size. Now that you mention it, I'm not even sure if that the 
original author intended this to be in bytes or kilobytes. My gut 
feeling is that 1536 bytes is a very small stack, and 1536 kB is a very 
large stack. I always assumed that the intention was to make the stack 
smaller than the default (which is, if I understand the documentation 
correct -- and the documentation corresponds to reality) 1024 kB, to 
make apps that spawn a large number of threads take less memory. But if 
your statement is correct it is actually making the stacks 50% larger!

Maybe I need to expand on this patch a bit and check different values of 
the stack size. And maybe we should not even set the argument at all, if 
we can build correctly without it.

Do you see any reason to keep the argument if we can build fine without it?

/Magnus
>
> Cheers,
> David
>
>> /Magnus
>>
>> [1] 
>> https://docs.oracle.com/en/java/javase/14/docs/specs/man/java.html#extra-options-for-java 
>>