orb/www/design/ThreadPool.html at master · eclipse-ee4j/orb · GitHub

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  <HEAD>
         <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1">
         <META NAME="Author" CONTENT="Dhiru Pandey">
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         <TITLE>ThreadPool Element in Server.xml</TITLE>
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  <BODY BACKGROUND="images/backgrounds/p12c08.gif">
         <H1> ThreadPool Configuration in the Application Server</H1>
         <H2> Introduction</H2> Based on discussions and collective agreement, it is
         felt that the ThreadPool should really be a separate element in the server.xml
         instead of getting bundled in with the ORB element as it exists today in S1AS
         7.0.
         <P>This document describes why this is useful to do and how this could be
                achieved. </P>
         <H2> ThreadPool configuration and DTD</H2> If ThreadPool was made a
         separate element in the server.xml it would allow the user to configure more
         than one ThreadPools (if required) and associate these threadpools to other
         components of the Application Server (ORB, Connectors etc.). This would
         encourage code re-use as well as give the user controls to tune the Application
         Server based on the load in the system and in different sub-systems (ORB,
         Connectors etc.). Inherent advantages offered by this scheme:
         <UL>
                <LI> One single place for the user to specify different threadpools
                  configuration params</LI>
                <LI> Ability to have multiple threadpools. This will aid in starvation
                  problems and help improve performace (ECPerf)</LI>
                <LI> Ability to dedicate threadpools/work-queues to App. server
                  components and EJB beans if desired.</LI>
                <LI> Allow monitoring and administration on the
                  threadpool/work-queues</LI>
         </UL> The DTD given below describes the ThreadPool configuration element.
         This element would be at the same level as the other components like
         http-service, iiop-service, web-container, ejb-container etc. in the S1AS 8.0
         server.xml DTD (<A
         HREF="http://iaseng.red.iplanet.com/apollo/config/sun-server_8_0.dtd">http://iaseng.red.iplanet.com/apollo/config/sun-server_8_0.dtd</A>):
         <BR>&nbsp;
         <P><FONT COLOR="#000099">&lt;!ELEMENT thread-pool-config
                (thread-pool+)&gt;</FONT> </P>
         <P><FONT COLOR="#000099">&lt;!--</FONT> <BR><FONT
                COLOR="#000099">&nbsp;&nbsp;&nbsp;&nbsp;
                thread-pool-id&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                This is an id for the work-queue e.g. "thread-pool-1", "thread-pool-2"
                etc</FONT> <BR><FONT COLOR="#000099">&nbsp;&nbsp;&nbsp;&nbsp;
                min-thread-pool-size&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                Minimum number of threads in the threadpool servicing requests in this
                queue.</FONT> <BR><FONT
                COLOR="#000099">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                These are created up front when this threadpool is instantiated</FONT>
                <BR><FONT COLOR="#000099">&nbsp;&nbsp;&nbsp;&nbsp;
                max-thread-pool-size&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                Maximum number of threads in the threadpool servicing requests in this
                queue</FONT> <BR><FONT
                COLOR="#000099">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                This is the upper bound on the no. of threads that exist in the
                threadpool.</FONT> <BR><FONT COLOR="#000099">&nbsp;&nbsp;&nbsp;&nbsp;
                idle-thread-timeout-in-seconds&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; idle threads are
                removed from pool, after this time</FONT> <BR><FONT
                COLOR="#000099">&nbsp;&nbsp;&nbsp;&nbsp;
                num-work-queues&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                This denotes the total number of work queues that are serviced by this
                threadpool.</FONT> <BR><FONT
                COLOR="#000099">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                Default value would be 1</FONT> <BR><FONT COLOR="#000099">--&gt;</FONT> </P>
         <P><FONT COLOR="#000099">&lt;!ELEMENT thread-pool(EMPTY)&gt;</FONT>
                <BR><FONT COLOR="#000099">&lt;!ATTLIST thread-pool&nbsp;
                thread-pool-id&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                CDATA&nbsp;&nbsp;&nbsp;&nbsp; #REQUIRED</FONT> <BR><FONT
                COLOR="#000099">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                min-thread-pool-size&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                CDATA&nbsp;&nbsp;&nbsp;&nbsp; "0"</FONT> <BR><FONT
                COLOR="#000099">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                max-thread-pool-size&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                CDATA&nbsp;&nbsp;&nbsp;&nbsp; "200"</FONT> <BR><FONT
                COLOR="#000099">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                idle-thread-timeout-in-seconds&nbsp; CDATA&nbsp;&nbsp;&nbsp;&nbsp; "120"</FONT>
                <BR><FONT
                COLOR="#000099">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                num-work-queues&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                CDATA&nbsp;&nbsp;&nbsp;&nbsp; "1"&gt;</FONT> </P>
         <P><FONT COLOR="#000099">&lt;!--&nbsp; The ORB element would look like
                ...</FONT> </P>
         <P><FONT COLOR="#000099">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                use-thread-pool-ids&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                This would refer to the thread-pool-id(s) defined in the thread-pool
                sub-element of</FONT> <BR><FONT
                COLOR="#000099">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                thread-pool-config element in server.xml. These would be the threadpool(s) used
                by the</FONT> <BR><FONT
                COLOR="#000099">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                ORB. More than one thread-pool-id(s) could be specified by using commas to
                separate</FONT> <BR><FONT
                COLOR="#000099">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                the names e.g. "orb-thread-pool-1, orb-thread-pool-2"</FONT> <BR><FONT
                COLOR="#000099">--&gt;</FONT> </P>
         <P><FONT COLOR="#000099">&lt;!ELEMENT orb (property*)&gt;</FONT> <BR><FONT
                COLOR="#000099">&lt;!ATTLIST orb&nbsp;
                message-fragment-size&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                CDATA&nbsp;&nbsp;&nbsp;&nbsp; "1024"</FONT> <BR><FONT
                COLOR="#000099">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                use-thread-pool-ids&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                IDREFS&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; #REQUIRED</FONT>
                <BR><FONT
                COLOR="#000099">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                max-connections&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                CDATA&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; "1024"</FONT> <BR><FONT
                COLOR="#000099">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                ....</FONT> <BR><FONT
                COLOR="#000099">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                ...&gt;</FONT> </P>
         <P>Essentially, thread-pool-config is a server wide element, that consists
                of atleast 1 or more thread-pool elements. </P>
         <P>A ThreadPoolManagerImpl class could be used as a singleton instance, to
                create all the ThreadPools at server startup using the configuration parameters
                defined in the threadpool-config element of the server.xml. Any component can
                then get the threadpool instance by providing the threadpool-id to this
                singleton ThreadPoolManager instance. Using this threadpool instance a work
                queue serviced by this threadpool can be obtained. Work can be added to the
                queue and it will get processed by the threads of the threadpool. </P>
         <P>EJB descriptors (or module descriptors - not sure if there is anything
                like this) could use the threadpool-ids defined in the server.xml to denote if
                the EJB (module) would want to use a dedicated threadpool. This could be done
                to avoid starvation. If nothing is specified or incorrect threadpool-id is
                specified in the bean descriptors, then the threadpool associated with the ORB
                will be used to service requests from that bean. <BR>&nbsp; <BR>&nbsp; </P>
         <H2> ThreadPoolManager SPI</H2> This section defines the ThreadPoolManager
         SPI. This SPI will be defined in com.sun.corba.ee.spi....(the exact package
         name is TBD)
         <P>This interface will be implemented by the ThreadPoolManagerImpl class in
                App. Server PE 8.0. It will be responsible for returning an instance of the
                ThreadPool given a thread-pool-id, from any component that wants to use a
                ThreadPool. In addition, ThreadPoolManagerImpl class will be responsible for
                creating all the threadpools (and their queues) at server startup time. This is
                done using the config bean that reads the thread-pool-config element in
                server.xml. ThreadPoolManager instance would be a singleton instance in the
                App. Server process. <BR>&nbsp; </P>
         <P><B><FONT COLOR="#009900">public interface ThreadPoolManager {</FONT></B>
                </P>
         <P><B><FONT COLOR="#009900">&nbsp;&nbsp;&nbsp; </FONT><FONT
                COLOR="#666666">/**</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp;
                * This method will return an instance of the threadpool given a
                threadpoolId,</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp; * that
                can be used by any component in the app. server.</FONT></B> <BR><B><FONT
                COLOR="#666666">&nbsp;&nbsp;&nbsp; */</FONT></B> <BR><B><FONT
                COLOR="#009900">&nbsp;&nbsp;&nbsp; public ThreadPool getThreadPool(String
                threadpoolId);</FONT></B> </P>
         <P><B><FONT COLOR="#009900">&nbsp;&nbsp;&nbsp; </FONT><FONT
                COLOR="#666666">/**</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp;
                * This method will return an instance of the threadpool given a numeric
                threadpoolId.</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp; * This
                method will be used by the ORB to support the functionality of</FONT></B>
                <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp; * dedicated threadpool for EJB
                beans</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp; */</FONT></B>
                <BR><B><FONT COLOR="#009900">&nbsp;&nbsp;&nbsp; public ThreadPool
                getThreadPool(int numericIdForThreadpool);</FONT></B> </P>
         <P><B><FONT COLOR="#009900">&nbsp;&nbsp;&nbsp; </FONT><FONT
                COLOR="#666666">/**</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp;
                * This method is used to return the numeric id of the threadpool, given a
                String</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp; *
                threadpoolId. This is used by the POA interceptors to add the numeric
                threadpool</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp; * Id, as
                a tagged component in the IOR. This is used to provide the functionality
                of</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp; * dedicated
                threadpool for EJB beans</FONT></B> <BR><B><FONT
                COLOR="#666666">&nbsp;&nbsp;&nbsp; */</FONT></B> <BR><B><FONT
                COLOR="#009900">&nbsp;&nbsp;&nbsp; public int&nbsp; getNumericId(String
                threadpoolId);</FONT></B> </P>
         <P><B><FONT COLOR="#009900">&nbsp;&nbsp;&nbsp; </FONT><FONT
                COLOR="#666666">/**</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp;
                * Return a String Id for a numericId of a threadpool managed by the
                threadpool</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp; *
                manager</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp;
                */</FONT></B> <BR><B><FONT COLOR="#009900">&nbsp;&nbsp;&nbsp; public String
                getStringId(int numericIdForThreadpool);</FONT></B> </P>
         <P><B><FONT COLOR="#009900">&nbsp;&nbsp;&nbsp; </FONT><FONT
                COLOR="#666666">/**</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp;
                * Returns the first instance of ThreadPool in the ThreadPoolManager</FONT></B>
                <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp; */</FONT></B> <BR><B><FONT
                COLOR="#009900">&nbsp;&nbsp;&nbsp; public ThreadPool
                getDefaultThreadPool();</FONT></B> </P>
         <P><B><FONT COLOR="#009900">}</FONT></B> </P>
         <P>An implementation of this SPI will also exist in the ORB that ships with
                J2SE, so that the ORB code that uses these API does not change for J2SE.
                <BR>&nbsp; </P>
         <H2> ThreadPool SPI</H2> This section defines the ThreadPool SPI. This SPI
         will be defined in com.sun.corba.ee.spi....(the exact package name is TBD)
         <P>The ORB already has plans for having an interface like that as part of
                the work being done on the design of the ORB transport. I am adding more APIs
                to the designed interface for this done by Harold Carr. </P>
         <P><B><FONT COLOR="#009900">public interface ThreadPool {</FONT></B> </P>
         <P><B><FONT COLOR="#009900">&nbsp;&nbsp;&nbsp; </FONT><FONT
                COLOR="#666666">/**</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp;
                * This method will return any instance of the WorkQueue. If the
                ThreadPool</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp; *
                instance only services one WorkQueue then that WorkQueue instance
                will</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp; * be returned.
                If there are more than one WorkQueues serviced by this</FONT></B> <BR><B><FONT
                COLOR="#666666">&nbsp;&nbsp;&nbsp; * ThreadPool, then this method would return
                a WorkQueue based on the</FONT></B> <BR><B><FONT
                COLOR="#666666">&nbsp;&nbsp;&nbsp; * implementation of the class that
                implements this interface. For PE 8.0 we</FONT></B> <BR><B><FONT
                COLOR="#666666">&nbsp;&nbsp;&nbsp; * would return a WorkQueue in a roundrobin
                fashion everytime this method</FONT></B> <BR><B><FONT
                COLOR="#666666">&nbsp;&nbsp;&nbsp; * is called. In the future we could allow
                pluggability of&nbsp; Policy objects for this.</FONT></B> <BR><B><FONT
                COLOR="#666666">&nbsp;&nbsp;&nbsp; */</FONT></B> <BR><B><FONT
                COLOR="#009900">&nbsp;&nbsp;&nbsp; public WorkQueue
                getAnyWorkQueue();</FONT></B> </P>
         <P><B><FONT COLOR="#009900">&nbsp;&nbsp;&nbsp; </FONT><FONT
                COLOR="#666666">/**</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp;
                * This method will return an instance of the of the WorkQueue given a
                queueId.</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp; * This will
                be useful in situations where there are more than one WorkQueues</FONT></B>
                <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp; * managed by the ThreadPool and
                the user of the ThreadPool wants to always use</FONT></B> <BR><B><FONT
                COLOR="#666666">&nbsp;&nbsp;&nbsp; * the same WorkQueue for doing the
                Work.</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp; * If the
                number of WorkQueues in the ThreadPool are 10, then queueIds will go</FONT></B>
                <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp; * from 0-9</FONT></B>
                <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp; */</FONT></B> <BR><B><FONT
                COLOR="#009900">&nbsp;&nbsp;&nbsp; public WorkQueue getWorkQueue(int
                queueId);</FONT></B> </P>
         <P><B><FONT COLOR="#009900">&nbsp;&nbsp;&nbsp; </FONT><FONT
                COLOR="#666666">/**</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp;
                * This method will return the number of WorkQueues serviced by the
                threadpool.</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp;
                */</FONT></B> <BR><B><FONT COLOR="#009900">&nbsp;&nbsp;&nbsp; public int
                numberOfWorkQueues();</FONT></B> </P>
         <P><B><FONT COLOR="#009900">&nbsp;&nbsp;&nbsp; </FONT><FONT
                COLOR="#666666">/**</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp;
                * This method will return the minimum number of threads maintained by the
                threadpool.</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp;
                */</FONT></B> <BR><B><FONT COLOR="#009900">&nbsp;&nbsp;&nbsp; public int
                minimumNumberOfThreads();</FONT></B> </P>
         <P><B><FONT COLOR="#009900">&nbsp;&nbsp;&nbsp; </FONT><FONT
                COLOR="#666666">/**</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp;
                * This method will return the maximum number of threads in the threadpool at
                any</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp; * point in time,
                for the life of the threadpool</FONT></B> <BR><B><FONT
                COLOR="#666666">&nbsp;&nbsp;&nbsp; */</FONT></B> <BR><B><FONT
                COLOR="#009900">&nbsp;&nbsp;&nbsp; public int
                maximumNumberOfThreads();</FONT></B> </P>
         <P><B><FONT COLOR="#009900">&nbsp;&nbsp;&nbsp; </FONT><FONT
                COLOR="#666666">/**</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp;
                * This method will return the time in milliseconds when idle threads in the
                threadpool are</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp; *
                removed.</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp;
                */</FONT></B> <BR><B><FONT COLOR="#009900">&nbsp;&nbsp;&nbsp; public long
                idleTimeoutForThreads();</FONT></B> </P>
         <P><B><FONT COLOR="#009900">&nbsp;&nbsp;&nbsp; </FONT><FONT
                COLOR="#666666">/**</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp;
                * This method will return the current number of threads in the threadpool. This
                method</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp; * returns a
                value which is not synchronized.</FONT></B> <BR><B><FONT
                COLOR="#666666">&nbsp;&nbsp;&nbsp; */</FONT></B> <BR><B><FONT
                COLOR="#009900">&nbsp;&nbsp;&nbsp; public int
                currentNumberOfThreads();</FONT></B> </P>
         <P><B><FONT COLOR="#009900">&nbsp;&nbsp;&nbsp; </FONT><FONT
                COLOR="#666666">/**</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp;
                * This method will return the number of available threads in the threadpool
                which are</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp;&nbsp; *
                waiting for work. This method returns a value which is not
                synchronized.</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp;
                */</FONT></B> <BR><B><FONT COLOR="#009900">&nbsp;&nbsp;&nbsp; public int
                numberOfAvailableThreads();</FONT></B> </P>
         <P><B><FONT COLOR="#009900">&nbsp;&nbsp;&nbsp; </FONT><FONT
                COLOR="#666666">/**</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp;
                * This method will return the number of busy threads in the
                threadpool</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp; * This
                method returns a value which is not synchronized.</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp;
                */</FONT></B> <BR><B><FONT COLOR="#009900">&nbsp;&nbsp;&nbsp; public int
                numberOfBusyThreads();</FONT></B> </P>
         <P><B><FONT COLOR="#009900">&nbsp;&nbsp;&nbsp; </FONT><FONT
                COLOR="#666666">/**</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp;
                * This method returns the number of Work items processed by the
                threadpool</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp;
                */</FONT></B> <BR><B><FONT COLOR="#009900">&nbsp;&nbsp;&nbsp; public long
                currentProcessedCount();</FONT></B> </P>
         <P><B><FONT COLOR="#009900">&nbsp;&nbsp;&nbsp; </FONT><FONT
                COLOR="#666666">/**</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp;
                * This method will return the name of the threadpool.</FONT></B> <BR><B><FONT
                COLOR="#666666">&nbsp;&nbsp;&nbsp; */</FONT></B> <BR><B><FONT
                COLOR="#009900">&nbsp;&nbsp;&nbsp; public String getName();</FONT></B> </P>
         <P><B><FONT COLOR="#009900">}</FONT></B> <BR>&nbsp; </P>
         <H2> WorkQueue SPI</H2> This section defines the WorkQueue SPI. This SPI
         will be defined in com.sun.corba.ee.spi....(the exact package name is TBD)
         <P>The ORB already has plans for having an interface like that as part of
                the work being done on the design of the ORB transport by Harold Carr. The
                following has been borrowed from that design </P>
         <P><B><FONT COLOR="#009900">public interface WorkQueue {</FONT></B> </P>
         <P><B><FONT COLOR="#009900">&nbsp;&nbsp;&nbsp; </FONT><FONT
                COLOR="#666666">/**</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp;
                * This method is used to add work to the WorkQueue</FONT></B> <BR><B><FONT
                COLOR="#666666">&nbsp;&nbsp;&nbsp; */</FONT></B> <BR><B><FONT
                COLOR="#009900">&nbsp;&nbsp;&nbsp; public void addWork(Work
                aWorkItem);</FONT></B> </P>
         <P><B><FONT COLOR="#009900">&nbsp;&nbsp;&nbsp; </FONT><FONT
                COLOR="#666666">/**</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp;
                * This method will return the name of the WorkQueue.</FONT></B> <BR><B><FONT
                COLOR="#666666">&nbsp;&nbsp;&nbsp; */</FONT></B> <BR><B><FONT
                COLOR="#009900">&nbsp;&nbsp;&nbsp; public String getName();</FONT></B> </P>
         <P><B><FONT COLOR="#009900">&nbsp;&nbsp;&nbsp; </FONT><FONT
                COLOR="#666666">/**</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp;
                * Returns the total number of Work items added to the Queue.</FONT></B>
                <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp; */</FONT></B> <BR><B><FONT
                COLOR="#009900">&nbsp;&nbsp;&nbsp; public long
                totalWorkItemsAdded();</FONT></B><B><FONT COLOR="#009900"></FONT></B> </P>
         <P><B><FONT COLOR="#009900">&nbsp;&nbsp;&nbsp; </FONT><FONT
                COLOR="#666666">/**</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp;
                * Returns the total number of Work items in the Queue to be
                processed.</FONT></B> <BR><B><FONT COLOR="#666666">&nbsp;&nbsp;&nbsp;
                */</FONT></B> <BR><B><FONT COLOR="#009900">&nbsp;&nbsp;&nbsp; public int
                workItemsInQueue();</FONT></B><B><FONT COLOR="#009900"></FONT></B> </P>
         <P><B><FONT COLOR="#009900">}</FONT></B> <BR>&nbsp; </P>
         <H2> Work SPI</H2> This section defines the Work SPI. This SPI will be
         defined in com.sun.corba.ee.spi....(the exact package name is TBD)
         <P>The ORB already has plans for having an interface like that as part of
                the work being done on the design of the ORB transport by Harold Carr. The
                following has been borrowed from that design </P>
         <P><B><FONT COLOR="#009900">public interface Work {</FONT></B> </P>
         <P><B><FONT COLOR="#009900">&nbsp;&nbsp;&nbsp; public void
                doWork();</FONT></B> </P>
         <P><B><FONT COLOR="#009900">&nbsp;&nbsp;&nbsp; public String
                getName();</FONT></B> </P>
         <P><B><FONT COLOR="#009900">}</FONT></B> </P></BODY>
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