Websphere ejb pool -

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the documentation here http://www.ibm.com/support/knowledgecenter/ss7jfu_7.0.0/com.ibm.websphere.express.doc/info/exp/ae/rejb_ecnt.html mentions minimum of 50 , maximum of 500 instances created default per ejb.

lets @ given point of time 500 clients trying use service. mean here after @ time there 500 instances? or server destroy instances after period of time , when there no incoming clients?

after reading further came across called hard limit h forces/tells container not create more specified maximum number of instances.

so understood in case of 50,500

  1. at point there max number of instances(500).
  2. if more clients trying connect, server create new instance(501, 502, 503....) per client , destroy after serving client.

can tell me if right?

pooling ejb instances allow save system resources. let's need 100 instances of ejb @ given point. initialize beans, process logic , destroy them. if need additional 100 instances after that, need on again. puts strain on system resources.

when pool ejb instances, move in , out of pool maintained ejb container. active instances process incoming requests, while passive ones stay in pool. control size of pool, there should upper , lower bound on number of instances within pool.

consider default setting: minimum 50 instances , maximum 500 instances. when server starts up, there no instances of ejb on server. application gets concurrent requests/hits, pool size increases. let's assume there 30 concurrent hits. pool size stays @ 30. websphere not create additional instances maintain pool size @ minimum value. after that, assume concurrent hits increase 75 , drop below 50. @ point, websphere destroy additional 25 ejb instances , maintain pool size @ 50. now, if define lower limit 'h50' (hard limit), websphere expend resources create 50 ejb instances server/application starts up. therefore, pool size never drop below 50.

now let's @ upper limit, 500. number of concurrent hits increases, pool size grows , exceeds 500. beyond limit, websphere tries lower pool size destroying ejb instances become inactive (i.e. return pool). however, ejb instances can continue grow beyond limit. if have 600 concurrent requests, there 600 ejb instances. if falls 540, additional 60 beans destroyed. hard limit ('h500') ensures overflow never happens. upto 500 concurrent requests can handled @ pool's maximum size. additional requests must wait until ejb instance becomes inactive (i.e. returns pool).


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