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https://issues.apache.org/jira/browse/KNOX-1165?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16689527#comment-16689527
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ASF subversion and git services commented on KNOX-1165:
-------------------------------------------------------
Commit 1846718 from kris...@apache.org in branch 'knox/trunk'
[ https://svn.apache.org/r1846718 ]
KNOX-804 - KNOX-1165 - Update documentation for
org.apache.knox.gateway.shirorealm.KnoxCacheManager
> Another unnamed CacheManager already exists in the same VM
> ----------------------------------------------------------
>
> Key: KNOX-1165
> URL: https://issues.apache.org/jira/browse/KNOX-1165
> Project: Apache Knox
> Issue Type: Bug
> Components: Server, Site
> Affects Versions: 0.12.0, 0.13.0, 0.14.0, 1.0.0, 1.1.0
> Environment: JDK 1.8
> CentOS-6 (64bit)
> Reporter: Ernani Pereira de Mattos Junior
> Assignee: Kevin Risden
> Priority: Critical
> Fix For: 1.2.0
>
>
> *Solution:* See updated documentation here:
> https://knox.apache.org/books/knox-1-2-0/user-guide.html#LDAP+Authentication+Caching
> *Problem*
> Issue is described on the note "Error:Shiro environment initialization
> failed" when starting Knox;
> {code:java}
> ERROR env.EnvironmentLoader (EnvironmentLoader.java:initEnvironment(146)) -
> Shiro environment initialization failed
> org.apache.shiro.cache.CacheException: net.sf.ehcache.CacheException:
> Another unnamed CacheManager already exists in the same VM. Please provide
> unique names for each CacheManager in the config or do one of following {code}
> After implementing the solution of creating a new ehcache.xml and reference
> as <ehcache name="knox-mytopology1"> we still see the issue:
> {code:java}
> Caused by: net.sf.ehcache.CacheException: Another CacheManager with same name
> 'knox-tp' already exists in the same VM. Please provide unique names for each
> CacheManager in the config or do one of following: {code}
> *Steps to reproduce*
> When enabling the following parameters:
> {code:java}
> <param>
> <name>main.cacheManager</name>
> <value>org.apache.shiro.cache.ehcache.EhCacheManager</value>
> </param>
> <param>
> <name>main.securityManager.cacheManager</name>
> <value>$cacheManager</value>
> </param>
> <param>
> <name>main.ldapRealm.authenticationCachingEnabled</name>
> <value>true</value>
> </param>{code}
> *More Info*
> This KNOX-804 was open to solve this same issue but is not documented
> anywhere, but we can see the coding changes in GitHub.
> * The issue seems to be a racing condition on the Shiro lib class, in which
> depending on the processing power of the server there are two threads within
> the same "if" statement;
> ** ref:
> [https://github.com/apache/shiro/blob/master/support/ehcache/src/main/java/org/apache/shiro/cache/ehcache/EhCacheManager.java]
> * The Default constructor only builds the Object, and does not do much:
> *
> {code:java}
> /**Default no argument constructor*/
> public EhCacheManager() {
> }{code}
> * Accordingly with shiro documentation:
> **
> {code:java}
> /**
> Initializes this instance.
> <p/>
> If a {@link #setCacheManager CacheManager} has been explicitly set (e.g. via
> Dependency Injection or programmatically) prior to calling this
> method, this method does nothing.
> <p/>
> However, if no {@code CacheManager} has been set, the default Ehcache
> singleton will be initialized, where Ehcache will look for an {@code
> ehcache.xml} file at the root of the classpath. If one is not found, Ehcache
> will use its own failsafe configuration file.
> <p/>
> Because Shiro cannot use the failsafe defaults (fail-safe expunges cached
> objects after 2 minutes, something not desirable for Shiro sessions), this
> class manages an internal default configuration for this case.
> @throws org.apache.shiro.cache.CacheException if there are any
> CacheExceptions thrown by EhCache.
> @see net.sf.ehcache.CacheManager#create
> */
> public final void init() throws CacheException { ensureCacheManager(); }
> private net.sf.ehcache.CacheManager ensureCacheManager()
> { ***It fails in here. }{code}
> * This is the head of the exception: The source of the existing CacheManager
> is:
> **
> {code:java}
> InputStreamConfigurationSource [stream=java.io.BufferedInputStream@675ffd1d]
> at
> org.apache.shiro.cache.ehcache.EhCacheManager.ensureCacheManager(EhCacheManager.java:224)
> at
> org.apache.shiro.cache.ehcache.EhCacheManager.init(EhCacheManager.java:199)
> at org.apache.shiro.util.LifecycleUtils.init(LifecycleUtils.java:45) at
> org.apache.shiro.util.LifecycleUtils.init(LifecycleUtils.java:40){code}
> * Starting from KNOX-804, the KnoxCacheManager was introduced. Remember that
> Init() will do nothing if anything in case the setCacheManager is explicitly
> set.
> ** ref:
> [https://github.com/apache/knox/commit/f9d8e07d768459240c8665f139cc140575dc5216]
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