Speed up concurrent pool creation #204
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Initializing multiple pools in parallel incurred significant lock contention on `poolMap` because this lock was held while any `Pool` was being constructed (which could take several seconds). Because of this, connecting to independent databases in parallel was not possible (Pool creation was serialized), severely limiting overall performance. *Changes* * Add `PoolHolder` to defer creation of `Pool` and act as a lock for each pool key. * Insert a new `PoolHolder` while holding the `poolMap` lock, reducing global thread contention. * Threads looking up the same key will acquire the same `PoolHolder` and that `PoolHolder` will ensure that only one `Pool` is created. Threads looking up unrelated `PoolHolder` will not be blocked by `Pool` creation. * Make registerJxm/unRegisterJmx thread safe. When Pool creation happened in parallel, there were errors in the logs because `Pool` was attempted to be registered more than one. *Testing* This change should have no impact on functionality. Performance should be improved when creating many Pools in parallel. Performance should remain the same when creating `Pool` instances sequentially. * Unit test added to validate that many pools can be created in parallel without issue. * Tested against ~20 real DB servers and saw performance improvement. All connections were created at the same time on separate threads.
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nice addition. thanks |
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Initializing multiple pools in parallel incurred significant lock contention on
poolMapbecause this lock was held while anyPoolwas being constructed (which could take several seconds).Because of this, connecting to independent databases in parallel was not possible (Pool creation was serialized), severely limiting overall performance.
Changes
PoolHolderto defer creation ofPooland act as a lock for each pool key.PoolHolderwhile holding thepoolMaplock, reducing global thread contention.PoolHolderand thatPoolHolderwill ensure that only onePoolis created. Threads looking up unrelatedPoolHolderwill not be blocked byPoolcreation.Poolwas attempted to be registered more than one.Testing
This change should have no impact on functionality. Performance should be improved when creating many Pools in parallel. Performance should remain the same when creating
Poolinstances sequentially.