RFR: 8358680: AOT cache creation fails: no strings should have been added

[Vladimir Kozlov]

On Mon, 16 Jun 2025 03:30:40 GMT, Ioi Lam <iklam at openjdk.org> wrote:

> Background: when writing the string table in the AOT cache, we do this:
> 
> 1. Find out the number of strings in the interned string table
> 2. Allocate Java object arrays that are large enough to store these strings. These arrays are used by `StringTable::lookup_shared()` in the production run.
> 3. Enter safepoint
> 4. Copy the strings into the arrays
> 
> This bug happened because:
> 
> - Step 1 is not thread safe, so it may be reading a stale version of `_items_count`
> - JIT compiler threads may create more interned strings after step 1
> 
> This PR attempts to fix both issues.

Can something else add string to table between you get number and safe point? How you avoid that?
I assume you can't get number at safepoint because you need to allocate object array not at safepoint. Right?

-------------

PR Comment: https://git.openjdk.org/jdk/pull/25816#issuecomment-2975115032