[master] RFR: OMWorld: Decouple deflation and table sizing

[Coleen Phillimore]

On Thu, 23 May 2024 06:32:28 GMT, Axel Boldt-Christmas <aboldtch at openjdk.org> wrote:

> The change reverts all changes to deflation and moves the resizing of the OMWorld ConcurrentHashTable to the service thread. Using a similar logic to how we resize the Symbol- and StringTables. 
> 
> The option to shrink the table is taken out and can be reintroduced at a later date as an enhancement. To do it correctly the interactions with deflation needs to be figured out.

This does simplify the table to act like the symbol and string tables, until we find we need to do something more complicated.

src/hotspot/share/runtime/serviceThread.cpp line 205:

> 203:     if (omworldtable_work) {
> 204:       LightweightSynchronizer::resize_table(jt);
> 205:     }

The monitor deflation thread seems like it would be a better place to do the OMWorld table resizing, because it also does cleaning that might be a response to monitor deflation.  The ServiceThread does a lot, and the OMWorld table might notice the stall.  The other thread is also a service thread in a way, so I think this could be moved there instead.

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PR Review: https://git.openjdk.org/lilliput/pull/175#pullrequestreview-2074817118
PR Review Comment: https://git.openjdk.org/lilliput/pull/175#discussion_r1612193671