RFR: 8218173: exception during StringConcatFactory clinit breaks string concat with no fallback

[Jim Laskey]

+1


> On May 19, 2020, at 10:59 AM, Claes Redestad <claes.redestad at oracle.com> wrote:
> 
> Hi,
> 
> while hard to reproduce, it's possible to break the StringConcatFactory
> if trying to bootstrap a concatenation when the VM is in such a state
> that any allocation will throw an OOME
> 
> By eagerly initializing the default strategy classes during bootstrap,
> while lazily initializing any method handles it uses in a way that
> allows retries later if that fail, we should minimize the risk of this,
> while ensuring we can recuperate.
> 
> This loads and initializes a few more classes eagerly on bootstrap, but
> the initial startup cost of that sits well below 0.1ms (amortized on
> first concat bootstrap), which seems a reasonable cost for increased
> stability in constrained environments.
> 
> I've not attempted a fix for the non-default strategies. Our intent is
> to remove these alternative strategies.
> 
> Bug:    https://bugs.openjdk.java.net/browse/JDK-8218173
> Webrev: http://cr.openjdk.java.net/~redestad/8218173/open.00/
> 
> Testing: tier1-3
> 
> This might also resolve https://bugs.openjdk.java.net/browse/JDK-8218176
> - so I included the removal of TestStressG1Humongous from ProblemList-
> graal.txt. I've run it a few times locally and in our CI without issue,
> but we probably need to enable it for while to determine if the
> intermittent issue is gone for good (or if we just move the issue
> somewhere else).
> 
> Thanks!
> 
> /Claes