Ernani Pereira de Mattos Junior created KNOX-1165:
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Summary: Knox - 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: KnoxSSO, Server
Affects Versions: 0.12.0
Environment: JDK 1.8
CentOS-6 (64bit)
Reporter: Ernani Pereira de Mattos Junior
Priority: Critical
PROBLEM:
Issue is described on the note ""Error:Shiro environment initialization failed"
when starting KNOX";
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:
After implementing the solution of creating a new ehcache.xml and reference as
<ehcache name="knox-mytopology1"> we still see the issue:
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:
STEPS TO REPRODUCE:
When enabling the following parameters:
<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>
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
1. The Default constructor only builds the Object, and does not do much:
/**
* Default no argument constructor
*/
public EhCacheManager() {
}
2. Accordingly with shiro documentation:
/**
* 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.
}
2.1 This is the head of the exception:
The source of the existing CacheManager is: 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)
3. Starting from Knox-804, the KnoxCacheManager was introduced.
public class KnoxCacheManager extends EhCacheManager {
+
+ public KnoxCacheManager() {
+ setCacheManager(net.sf.ehcache.CacheManager.create());
+ }
+}
*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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