RFR (XXS): 8205633: TestOptionsWithRanges.java of '-XX:TLABSize=2147483648' fails intermittently

[Kim Barrett]

> On Aug 9, 2018, at 6:47 AM, Thomas Schatzl <thomas.schatzl at oracle.com> wrote:
> 
> Hi all,
> 
>  can I have reviews for this tiny change that excludes maximum range
> testing for the TLABSize option from TestOptionsWithRanges?
> 
> Manually setting TLABSize forces the VM in serial, parallel and cms to
> use that TLAB size. This means that for ergonomically determined heap
> sizes, there is a high chance that a single java thread allocating a
> TLAB will exhaust eden. Another Java thread allocating objects would in
> the normal case cause a GC, but when we are starting up, we can't do a
> GC yet and error out as described in the bug.
> 
> The suggested fix is to disable doing the maximum range check for
> TLABSize in the test because
> - there are setups where this TLAB size is valid (i.e. eden large
> enough)
> - otherwise limiting maximum TLAB size in these collectors could
> decrease performance; particularly at startup we can not determine a
> good value yet because eden has not been fully sized yet.
> 
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8205633
> Webrev:
> http://cr.openjdk.java.net/~tschatzl/8205633/webrev/
> Testing:
> Failing test case with serial/parallel/CMS 400 times without failure
> 
> Thanks,
>  Thomas

Looks good.