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Virtual heap size  XML
Forum Index -> Terracotta for Web Sessions
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srinathv77

neo

Joined: 12/14/2006 10:33:41
Messages: 3
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Hi Sir/Madam,
I wanted to know using Terracotta for session replication, will this give me unlimited virtual heap...If my Application Server is having 1.5 Gb can i keep upto consolidated 2 GB in session memory?

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Regards,
Sreenath.V
zeeiyer

consul

Joined: 05/24/2006 14:28:28
Messages: 493
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Yes - practically unlimited virtual heap. You are only bound theoretically by the size of the disk you can provision on your Terracotta server.

Terracotta Sessions is built on underlying core DSO (Distributed Shared Objects) technology and hence has the Virtual Memory feature baked into it - i.e. if your object graph (the collection containing all sessions) exceeds the size of your heap, portions of the object graph would reside on the Terracotta server and portions on disk and the appropriate portion (e.g. element of the collection) gets faulted in to a given application server's heap, on demand. As of today, we've tested this feature with object graphs in the range of 30G.

Hope that answers the question. Let us know if additional clarification is needed.
Regards,
Iyer.

Sreeni Iyer, Terracotta.
Not a member yet - Click here to join the Terracotta Community
srinathv77

neo

Joined: 12/14/2006 10:33:41
Messages: 3
Offline

First thanks to the reply. To make my self further clear, my App Server is having 1.5 GB heap size. Is there any configuration that i can specify in Terracotta to restrict my app server to 1 GB of session data and if it crosses 1 GB i want that to move to TerraCotta Server. So that i can use remaining 500 MB of heap for application data that gets created and destroyed for the request/response paradigm.

Regards,
Sreenath.V
zeeiyer

consul

Joined: 05/24/2006 14:28:28
Messages: 493
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Effectively yes. The config-settings are not that direct though.

You specify when the eviction from the L1 cache to the L2 happens as a % of heap (and also what percent needs to be evicted). e.g. the default settings are when 70% of heap utilization is reached , evict 10% of the clustered object-graph to the Terracotta server from the application server. You may set java system properties and override the defaults, if desired...(e.g. l1.cachemanager.threshold=70, l1.cachemanager.percentageToEvict=10)

Regards
Iyer.

Sreeni Iyer, Terracotta.
Not a member yet - Click here to join the Terracotta Community
srinathv77

neo

Joined: 12/14/2006 10:33:41
Messages: 3
Offline

Thanks alot.

Regards,
Sreenath.V
 
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