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List:       openjdk-hotspot-runtime-dev
Subject:    Re: RFR: 8277531: Print actual default stacksize on Windows thread logging
From:       David Holmes <david.holmes () oracle ! com>
Date:       2021-11-26 13:53:25
Message-ID: 75bf40e6-bf11-28b4-16e7-11e21a1d0ca0 () oracle ! com
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On 26/11/2021 10:33 pm, Takuya Kiriyama wrote:
> On Mon, 22 Nov 2021 09:22:39 GMT, Takuya Kiriyama <duke@openjdk.java.net> wrote:
> 
> > I modified to log actual stack size on Windows by using \
> > `os::win32::default_stack_size()`. Could you please review this fix?
> 
> Thank you so much for your review.
> Sorry it took me so long to understand discussion.
> 
> Is there something wrong to print out the value of default_stack_size?
> I could not confirm the problem when I combine -Xss with -XX:ThreadStackSize., but \
> it doesn't affect this patch.

The problem is that os:;win32::default_stack_size() doesn't necessarily 
report the default stack size - it simply reports the stackSize of the 
initial main JavaThread thread. So if you print it, it should only be 
for JavaThreads that are not CompilerThreads.

But if you run "java -Xss256k -XX:ThreadStackSize=512K" it will print 
256K as the default stack size when in fact all JavaThreads except the 
main thread will get a 512K stack because of ThreadStackSize.

So given you can't actually print a value that you know to be correct, 
it may be best just to leave this as "default" - and perhaps this is why 
it was that way to begin with.

Cheers,
David

> I will try to fix this test for -Xss, -XX:ThreadStackSize, \
> -XX:CompilerThreadStackSize and -XX:VMThreadStackSize. Please let me know if there \
> are any other options which need to be tested. 
> -------------
> 
> PR: https://git.openjdk.java.net/jdk/pull/6495
> 


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