Connection pool advanced settings
Use this page to specify connection pooling related settings.
This console page is common to a range of resource types: for example, JDBC data sources and JMS queue connection factories. To view this page, the path depends on the type of resource, but generally you select an instance of the resource provider, then an instance of the resource type, then click Connection pool properties > Advanced connection pool properties.
For example, click:
- Resources > JDBC > JDBC providers > JDBC_provider > Data sources > data_source > Connection pool properties > Advanced connection pool properties
- Resources > JMS > JMS provider > Default messaging > Queue connection factory > JMS_queue_connection_factory > Connection pool properties > Advanced connection pool properties.
The Connection Pool Partition Support creates buckets and hashes on the buckets for optimizing the connection pool for getConnection method requests. The number of shared partitions, the number of free pool partitions, and the free pool distribution table size are properties related to reducing the time a thread must wait for a synchronization lock. On systems with a single processor, these values do not make a difference. On systems with multiple processors, these settings can reduce the performance cost that is associated with managing multiple threads.
When the default values are used, which means that the partitions are set to 0, the connection pool automatically selects the best values. The ability to change the default values is primarily provided for connection pools that exceed 500 maximum connections. When the connection pool exceeds 500 maximum connections, the formula used for auto-tuning the connection pool might create large objects whose size you might want to reduce. Performance might be reduced by reducing the partition size. However, that impact is normal when you weigh memory versus performance.
Number of shared partitions
Number of partitions created in each of the shared pools.
Partition support is always enabled. The default values of 0 should be used to enable the connection pool to pick the best values for performance. In some cases where large multiprocessor systems are used, adjusting the partition support properties might help performance.
Information Value Data type integer Default value 0 Range 0 to max int
Number of free pool partitions
Number of partitions created in each of the free pools.
Information Value Data type integer Default value 0 Range 0 to max int
Free pool distribution table size
Determines the distribution of Subject and CRI hash values in the table that indexes connection usage data.
These hash values are used to match connection request credentials with the connections. A free pool distribution table size larger than 1 can yield more efficient distribution of hash values, to help minimize search collisions within the table. Fewer collisions can result in faster retrieval of a connection that matches a request. Use a larger value for free pool distribution table size if the resource receives many incoming requests with varying credentials. Smaller values (1) should be used if the same credentials apply to all incoming requests for the resource. The value of 0 means random distribution.
Information Value Data type integer Default value 0 Range 0 to max int
Surge threshold
Number of connections created before surge protection is activated.
Surge protection is designed to prevent overloading of a data source when too many connections are created at the same time. Surge protection is controlled by two properties, surge threshold and surge creation interval.
The surge threshold property specifies the number of connections created before surge protection is activated. After you reach the specified number of connections, you enter surge mode.
The surge creation interval property specifies the amount of time, in seconds, between the creation of connections when in surge mode.
For example, assume the follow settings:
- maxConnections = 50
- surgeThreshold = 10
- surgeCreationInterval = 30 seconds
If the connection pool receives 15 connection requests, 10 connections are created at about the same time. The 11th connection is created 30 seconds after the first 10 connections. The 12th connection is created 30 seconds after the 11th connection. Connections continue to be created every 30 seconds until there are no more new connections needed or you reach the maxConnections value.
Surge connection support starts if the surge threshold is > -1 and the surge creation interval is > 0. The surge threshold property has a default value of -1, which indicates that it is turned off.
Information Value Data type integer Default value -1 Range -1 to max int
Surge creation interval
Amount of time between connection creates when we are in surge protection mode.
When the number of connections specified for the surge threshold property is reached, the surge creation interval property dictates how much time each new connection request must wait before fulfillment.
Restriction: Surge protection does not work for a connection pool that is managed through an activation specification that coordinates with a JMS queue connection factory and default messaging provider. To control incoming connections for JMS calls such as onMessage, see the help topic for the console page JMS > Activation specification > activation_specification_name.
Information Value Data type integer Default value 0 Range 0 to max int
Stuck timer interval
A stuck connection is an active connection that is not responding or returning to the connection pool. If the pool is stuck (we have reached the stuck threshold), a resource exception is given to all new connection requests until the pool is unstuck. The stuck timer interval property is the interval for the timer, for example, how often the connection pool checks for stuck connections. The default value is 0 seconds.
If an attempt to change the stuck time, stuck timer interval, or stuck threshold properties using the wsadmin scripting tool fails, an IllegalState exception occurs. The pool cannot have any active requests or active connections during this request. For the stuck connection support to start, the stuck time and the stuck threshold property values must be greater than 0 and maximum connections must be greater than 0.
Also, the stuck timer interval, if it is set, must be less than the stuck time value. In fact, it is suggested that the stuck timer interval be one-quarter to one-sixth the value of stuck time so that the connection pool checks for stuck connections 4 - 6 times before a connection is declared stuck. This interval check reduces the likelihood of false positives.
Information Value Data type integer Default value 0 Range 0 to max int
Stuck time
A stuck connection is an active connection that is not responding or returning to the connection pool. If the pool is stuck (we have reached the stuck threshold), a resource exception is given to all new connection requests until the pool is unstuck. The stuck time property is the interval, in seconds, allowed for a single active connection to be in use to the backend resource before it is considered to be stuck.
Information Value Data type integer Default value 0 Range 0 to max int
Stuck threshold
A stuck connection is an active connection that is not responding or returning to the connection pool. If the pool is stuck (we have reached the stuck threshold), a resource exception is given to all new connection requests until the pool is unstuck. An application can explicitly catch this exception and continue processing. The pool continues to periodically check for stuck connections when the number of stuck connections is past the threshold. If the number of stuck connections drops below the stuck threshold, the pool detects this during its periodic checks and enables the pool to begin servicing requests again. The stuck threshold is the number of connections that must be considered stuck for the pool to be in stuck mode.
Information Value Data type integer Default value 0 Range 0 to max int
Related concepts
Relational resource adapters and JCA JDBC providers