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  1. Application Server 3 4 5 and 6
  2. JBAS-8866

JBoss Cache lock UpgradeException when simultaneous requests with the same SSO create new sessions



    • Bug
    • Resolution: Unresolved
    • Major
    • None
    • JBossAS-4.2.3.GA, JBossAS-5.1.0.GA
    • Clustering
    • None


      When more than one request with the same SSO ID creates a session at the same time, some may fail with an org.jboss.cache.lock.UpgradeException.

      The root cause is that TreeCacheSSOClusterManager.addSession/removeSession first get a read lock, then upgrade to a write lock.
      In 5.x, addSession is ok, only removeSession has this issue.

      The fix is to get a write lock up front, instead of starting with a read lock then upgrading.

      For AS 4.x, since JBoss Cache 1.4.x doesn't have Option.setForceWriteLock, adding something like the following
      before the cache.get should force a write lock:

      cache.put ( fqn, "LOCK", null, LOCAL_OPTION );

      [org.jboss.web.tomcat.service.sso.TreeCacheSSOClusterManager] caught exception adding session C4851CD53FB091272E78A9395C0C15F1 to SSO id 821E74E80D46822B77FB774E8AEF67D8
      Caused by: org.jboss.cache.lock.UpgradeException: failure upgrading lock: fqn=/SSO/821E74E80D46822B77FB774E8AEF67D8/sessions, caller=GlobalTransaction:<>:4, lock=read owners=[GlobalTransaction:<>:4, GlobalTransaction:<>:5] (activeReaders=1, activeWriter=null, waitingReaders=0, waitingWriters=1, waitingUpgrader=1)
      at org.jboss.cache.Node.acquire(Node.java:517)
      Caused by: org.jboss.cache.lock.UpgradeException: acquireWriteLock(): lock upgrade failed for /SSO/821E74E80D46822B77FB774E8AEF67D8/sessions (caller=GlobalTransaction:<>:4, lock info: read owners=[GlobalTransaction:<>:4, GlobalTransaction:<>:5] (activeReaders=1, activeWriter=null, waitingReaders=0, waitingWriters=1, waitingUpgrader=1))
      Caused by: org.jboss.cache.lock.UpgradeException: upgradeLockAttempt(): more than one reader trying to simultaneously upgrade to write lock
      at org.jboss.cache.lock.ReadWriteLockWithUpgrade.upgradeLockAttempt(ReadWriteLockWithUpgrade.java:106)
      at org.jboss.cache.lock.LockStrategyRepeatableRead.upgradeLockAttempt(LockStrategyRepeatableRead.java:43)
      at org.jboss.cache.lock.IdentityLock.acquireWriteLock(IdentityLock.java:175)


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              rhn-support-dereed Dennis Reed
              rhn-support-dereed Dennis Reed
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