fix: avoid too many concurrent db queries when cache becomes invalid#699
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fix: avoid too many concurrent db queries when cache becomes invalid#699
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In large installations it's more likely to process multiple storage_update events at the same time. When the storage mapping cache becomes invalid each of these events would try to query the database to update the cache. Apart from causing additional load on the database this would also exhaust sqlx's internal connection pool when more event handling threads are running than there are available database connections -- in this case the `Failed to query database: pool timed out while waiting for an open connection` message is logged. This commit changes how the storage mapping cache is updated once it becomes invalid by trying to reduce the chance of multiple threads querying the database at once. Other callers should then still retrieve the old cached mapping during the time the cache is updated. Signed-off-by: Jyrki Gadinger <nilsding@nilsding.org>
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In large installations it's more likely that multiple storage_update events are processed at the same time. When the storage mapping cache becomes invalid each of these events would try to query the database to update the cache.
Apart from causing additional load on the database this would also exhaust sqlx's internal connection pool when more event handling threads are running than there are available database connections -- in this case the
Failed to query database: pool timed out while waiting for an open connectionmessage is logged.This PR changes how the storage mapping cache is updated once it becomes invalid by trying to reduce the chance of multiple threads querying the database at once. Other callers should then still retrieve the old cached mapping during the time the cache is updated.