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https://issues.apache.org/jira/browse/GEODE-6594?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jacob S. Barrett reassigned GEODE-6594:
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Assignee: Jacob S. Barrett
> Simplify client connection pooling
> ----------------------------------
>
> Key: GEODE-6594
> URL: https://issues.apache.org/jira/browse/GEODE-6594
> Project: Geode
> Issue Type: Improvement
> Components: client/server
> Reporter: Jacob S. Barrett
> Assignee: Jacob S. Barrett
> Priority: Major
>
> Current client connection pooling is multi-layered. A {{Connection}} is
> wrapped in a pooled {PooledConnection}}. A {{PooledConnection}} is kept in
> primary pool in an {allConnections}} set and when unused it is also in the
> {{availableConnections}} deque. A {{PooledConnection}} can also be held in a
> thread local pool (secondary pool). If in a thread local pool then it is not
> in the primary pool's {{availableConnections}}. This arrangement between the
> secondary and primary pools results in complex relationships with expirations
> and rebalancing actions. Since GEODE-6515 thread local connections does not
> provide a performance boost over the primary pool anymore we should remove it
> entirely, thus simplifying these complexities.
> Idle connection timeouts must scan the {{allConnections}} set since the
> secondary may hold idle connections that won't be in the
> {{availableConnections}}. This requires scanning the entire set of
> connections with an exclusive lock, which can be really expensive for large
> connection pools. If there were no secondary pools we could scan the
> {{availableConnections}} deque in reverse order stopping at the first idle
> connection not exceeding the timeout limit. This scan would be lock free and
> would not touch every connection. The {{availableConnections}} deque is used
> as a LIFO queue so connections at the front are hot and connection at the end
> are cold.
> Connection lifetime expiration currently requires, again scanning the
> {{allConnections}} set with exclusive lock looking for connections that are
> over the lifetime limit. If the connection needs to be expired then the
> {{PooledConnection}} as its {{Connection}} swapped out for a new one to the
> same server. If we remove the secondary pool then expired connections could
> simply be removed from the {{availableConnections}} and {{allConnections}}
> and destroyed. A new connection would be created either on demand of from
> pre-fill. No complicated logic is required to support swapping out the
> underlying {{Connection}}.
> Currently load conditioning requires scanning the {{allConnections}} for N
> number of idle connections to specific servers. Each matching
> {{PooledConnection}} then has it's underlying {{Connection}} swapped out for
> one to a different server. This requires extra logic in the
> {{borrowConnection(forServer)}} method to check that the associated server
> hasn't changed between to matching and activation, if it has it must be
> placed back in the queue and the scan must be repeated. Removing the
> secondary pool will removed the need to swap out connections. Any matching
> idle connection from the {{availableConnections}} queue will just be
> destroyed. New connections will be created to the less loaded server either
> on demand or via pre-fill. No complicated logic for swapping connections is
> required and no recheck for chaining servers is required.
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