Separated Hazelcast's own session expiration from Tomcat #86
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Note that this change will break the functionality of having different session timeout for each session, see my previous note about that: #40 (comment) |
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@bergander thanks for the reminder. I added support for session specific timeout. |
| } catch (InvalidConfigurationException e) { | ||
| log.info("Max idle seconds cannot be setup, \"" + mapName | ||
| + "\" map is already configured in the Hazelcast cluster!"); | ||
| } |
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I believe that is not needed. On the fly MapConfig update is not persistent so it is not resilient to cluster restarts. We need to mention clearly that hazelcast config must be set with maxIdleSeconds that is greater than session timeout. This can be added as an info to the log and updated in README.
README.md
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| @@ -196,6 +196,9 @@ Based on Tomcat configuration or `sessionTimeout` setting in `web.xml`, sessions | |||
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| `processExpiresFrequency`, which is defined in [`<Manager>`](#configuring-manager-element-for-tomcat), is the only setting that controls the behavior of session expiry policy in the Tomcat Web Session Replication Module. By setting this, you can set the frequency of the session expiration checks in the Tomcat Instance. | |||
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| Starting with v2.1, the session expiration in Hazelcast cluster is separated from the Tomcat control. Instead, Hazelcast's own expiry mechanism (`max-idle-seconds` property) is used. By default, `sessionTimeout` value is configured as the `max-idle-seconds` for the session map in Hazelcast. So, the session expiry in Hazelcast cluster happens at the same time with Tomcat by default. However, if you would like to change the expiration setting on the Hazelcast cluster, you need to configure eviction for the related session map. Please see the Hazelcast's own eviction mechanism details [here](https://docs.hazelcast.org/docs/latest/manual/html-single/#map-eviction). | |||
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Starting with v2.1, the session expiration in Hazelcast cluster is not controlled by Tomcat anymore. Instead, Hazelcast's own expiry mechanism (max-idle-seconds property) is used. if you would like to change the expiration setting on the Hazelcast cluster, you need to configure eviction for the related session map. Please see the Hazelcast's own eviction mechanism details [here](https://docs.hazelcast.org/docs/latest/manual/html-single/#map-eviction).
Maybe some shorter version like that can be a good option?
Before this change, Tomcat's background process for expiration was retrieving all the remote sessions to local to check & expire them. This can cause OOMEs when the total session size is larger than the local container's heap.
To prevent that, the expiration of the sessions in the Hazelcast cluster is separated from Tomcat. Now, Hazelcast's
max-idle-secondsproperty is set tosessionTimeoutvalue by default to define expiry policy on the cluster side. The configuration is done by adding a dynamic map config to the Hazelcast cluster if there is no configuration for this map in the cluster. If so, then the existing cluster configuration has the priority.Fixes #83.