Folks:
I have a few comments and questions about the connection pool features,
particularly from the perspective of HADB's use of the jdbc-resource and
connection-pool.
The high level question is: will we still be able to use the existing
non-clustered
connection pool with no issues of compatibility? We do not want to
introduce
any regressions caused by this new feature.
I am seeing some important problems in the semantics you propose for
the behavior of this clustered pool particularly if we tried to use it
with HADB.
For example, your one-pager has the following:
"The connections are load-balanced and failed-over to healthy nodes only
during connection request from the application. There is no fail-over
support for connections of in-flight transactions. ClusteredPool uses
the connection-validation feature of the connection pool. When a
connection is requested by the application, clustered-pool will choose a
pool from its list and validates the connection. If the validation is
successful, connection is returned to the user. If the connection is
invalid, clustered-pool will fail-over to other available pools. All
connections in the failed-pool will be dropped."
The problem here is that we already have (with HADB) a well-established
and tested mechanism whereby an attempt to create a connection will be
retried (and most often succeed) by our app server code calling through
the HADB JDBC driver. In this situation, it would be very very bad to
do what you state in the last sentence here: "All connections in the
failed-pool will be dropped."
There may be more semantic issues like this and we need to scrutinize
this very carefully,
especially if this new type of pool is to be the only choice in the future.
regards, Larry White
Jagadish Prasath Ramu wrote:
> Hi,
> We have proposed the one pager for connection pool features
> <http://www.glassfishwiki.org/gfwiki/attach/OnePagersOrFunctionalSpecs/ConnectionPoolOnePager.html>,
> which involves DTD changes. (diff attached)
>
> we have updated the "Domain Configuration Management Process" wiki
> page for GlassFish V2 Release
> <http://www.glassfishwiki.org/gfwiki/Wiki.jsp?page=GlassFishV2ApplicationServer9.1>
>
> Thanks,
> -Jagadish, Kshitiz
>
>------------------------------------------------------------------------
>
>------------------------------------------------------------------------------------------------------
>* DTD changes associated with clustered-pool
>
>554a555,560
>
>
>> attributes :
>> pool-name
>> the pool-id associated with the resource.
>> In case of clustered-pool, it can be a comma separated
>> list of available connection pools.
>>
>>
>>
>643a650,656
>
>
>> attributes
>>
>> pool-name
>> the pool-id associated with the resource.
>> In case of clustered-pool, it can be a comma separated
>> list of available connection pools.
>>
>>
>>
>
>Comments : This is only a description change. Now pool-name can take
>comma-separated connection-pool ids. The DTD has no impact as such.
>------------------------------------------------------------------------------------------------------
>
>
>* DTD change associated with introduction of sun-specific-property
>
>2569a2583,2621
>
>
>> sun-specific-property
>> To enable application server specific connection pool features.
>> (See <sun-specific-property>)
>>
>> The following are the names and corresponding description for these
>> properties
>>
>> LeakTracing
>> To aid user in detecting potential connection leaks by
>> application.
>>
>> ConnectionLeakTimeout
>> The period after which connection is considered to
>> be leaked.
>>
>> ConnectionCreationRetry
>> To retry connection creation for specific number of
>> times, at specified intervals
>>
>> ConnectionCreationRetryAttempts
>> The number of attempt to create a new connection
>> when requested by application
>>
>> ConnectionCreationRetryInterval
>> The time interval between successive retry to create
>> a connection
>>
>> ValidateAtmostPeriod
>> Validates atmost once in the specified time-interval
>>
>> StatementTimeout
>> Sets the timeout property of a connection to enable
>> termination of abnormally long running queries.
>>
>> PollInterval
>> The time interval between successive polling of failed node.
>> Applicable only for clustered pool.
>>
>>
>>
>2725c2777
>< <!ELEMENT jdbc-connection-pool (description?, property*)>
>---
>
>
>><!ELEMENT jdbc-connection-pool (description?, sun-specific-property* property*)>
>>
>>
>2762a2815,2849
>
>
>> sun-specific-property
>> To enable application server specific connection pool features.
>> (See <sun-specific-property>)
>>
>> The following are the names and corresponding description for these
>> properties
>>
>> LeakTracing
>> To aid user in detecting potential connection leaks by
>> application.
>>
>> ConnectionLeakTimeout
>> The period after which connection is considered to
>> be leaked.
>>
>> ConnectionCreationRetry
>> To retry connection creation for specific number of
>> times, at specified intervals
>>
>> ConnectionCreationRetryAttempts
>> The number of attempt to create a new connection
>> when requested by application
>>
>> ConnectionCreationRetryInterval
>> The time interval between successive retry to create
>> a connection
>>
>> ValidateAtmostPeriod
>> Validates atmost once in the specified time-interval
>>
>> PollInterval
>> The time interval between successive polling of failed node.
>> Applicable only for clustered pool.
>>
>>
>>
>2825c2912
>< <!ELEMENT connector-connection-pool (description?, security-map*, property*)>
>---
>
>
>><!ELEMENT connector-connection-pool (description?, security-map*, sun-specific-property*, property*)>
>>
>>
>2955a3043,3055
>
>
>><!-- sun-specific-property
>> Syntax for providing application server specific features for
>> connection-pool
>>
>> Used in:
>> connector-connection-pool, jdbc-connection-pool
>>
>>-->
>><!ELEMENT sun-specific-property (description?)>
>>
>><!ATTLIST sun-specific-property
>> name CDATA #REQUIRED
>> value CDATA #REQUIRED>
>>
>>
>
>Comments : The above is list of DTD changes for introduction of sun-specific property.
>An optional element sun-specific-property is introduced for jdbc and connector
>connection-pool. It is similar to element property. It will hold name and value pair.
>
>------------------------------------------------------------------------------------------------------
>
>