[jira] [Work logged] (WW-3576) SessionMap is not thread-safe

[ASF GitHub Bot (Jira)]

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https://issues.apache.org/jira/browse/WW-3576?focusedWorklogId=1005234&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-1005234
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ASF GitHub Bot logged work on WW-3576:
--------------------------------------

                Author: ASF GitHub Bot
            Created on: 15/Feb/26 15:13
            Start Date: 15/Feb/26 15:13
    Worklog Time Spent: 10m 
      Work Description: sonarqubecloud[bot] commented on PR #1577:
URL: https://github.com/apache/struts/pull/1577#issuecomment-3904658806

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Issue Time Tracking
-------------------

    Worklog Id:     (was: 1005234)
    Time Spent: 50m  (was: 40m)

> SessionMap is not thread-safe
> -----------------------------
>
>                 Key: WW-3576
>                 URL: https://issues.apache.org/jira/browse/WW-3576
>             Project: Struts 2
>          Issue Type: Bug
>          Components: Other
>    Affects Versions: 2.2.1
>            Reporter: Sylvain Veyrié
>            Assignee: Lukasz Lenart
>            Priority: Major
>             Fix For: 7.2.0
>
>          Time Spent: 50m
>  Remaining Estimate: 0h
>
> Searching for a bug after some stress test (Exception on "getAttribute": 
> already invalidated session), I reviewed SessionMap.java.
> Following WW-239, SessionMap has been made thread-safe.
> All methods are like this :
> public void doSomething() {
>       if (session == null) {
>               return;
>       }
>       
>       synchronized (session) {
>               session.doSometing();
>       }
> }
> For example:
> public void invalidate() {
>       if (session == null) {
>               return;
>       }
>       
>       synchronized (session) {
>               session.invalidate();
>               session = null;
>               entries = null;
>       }
> } 
> IMHO this is not thread-safe. With the example of invalidate(), if there is a 
> context switch just before the synchronized, the nullity is no more checked. 
> If another invalidate() is called at least a NPE can be thrown. There are 
> probably other side-effects like my exception problem.
> As now Struts 2 only supports Java 5+, there is two ways to fix it :
> * use a double-check-locking (DCL) and set session "volatile" (easy way)
> * use java.util.concurrent instead of synchronized keyword
> If you agree and choose one of those fixes, I can provide a patch.
> For the moment, I don't know if my bug is resolved if we directly use javax 
> session, without this wrapper.



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