RFR: 8355627: Don't use ThreadCritical for EventLog list [v2]

[Martin Doerr]

On Sat, 3 May 2025 01:57:53 GMT, Zhengyu Gu <zgu at openjdk.org> wrote:

>> Yes we only used ThreadCritical to add to the list after the VM becomes multithreaded.  The list traversals (reads) are for hs_err_pid file printing, which presumably is single threaded at that point and presumably nothing is adding to the list.  I added Atomic::load() but I think it's not necessary to be a load_acquire.
>> There are only about 10 items max on this list so far, so I think performance isn't a concern either way.
>
> There is also a jcmd to print out events. In theory, that could be a problem if  CAS is unordered.

Then, memory barriers on the reader's side should also be checked.

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PR Review Comment: https://git.openjdk.org/jdk/pull/24954#discussion_r2073046694