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https://issues.apache.org/jira/browse/OFBIZ-2186?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12680088#action_12680088
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David E. Jones commented on OFBIZ-2186:
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Thank you for the additional information.
Could you try the changes in SVN rev 751619? With this the LRUMap is made
synchronized using the Collections.synchronizedMap method when it is first
created, and that should make it thread safe (except for certain iteration
related operations, but we aren't doing those with the memoryTable field as far
as I can tell).
This should fix the synchronized get problem, and the separately monitored get
vs put/remove problem.
> OutOfMemory provoked by Cache overflow
> --------------------------------------
>
> Key: OFBIZ-2186
> URL: https://issues.apache.org/jira/browse/OFBIZ-2186
> Project: OFBiz
> Issue Type: Bug
> Components: framework
> Affects Versions: SVN trunk, Release Branch 4.0
> Environment: Linux, JDK 1.5_15, Xmx set to 1156Mo
> Reporter: Philippe Mouawad
> Priority: Critical
> Attachments: CacheLineTable-patch.txt, OfbizBug.zip
>
>
> In our production system, we had an OutOfMemoryError.
> I analyzed the generated Heap Dump and found the following:
> The cache entitycache.entity-list.default.ProductCategoryMember retains a
> heap of 369314128 Bytes.
> The LRUMap hold by this object is occupying this space (369314128) and this
> object has a stange state:
> - maxSize is set to 5000 (as set in the cache.properties)
> - size is 128930 => PROBLEM
> IN cache.properties:
> entitycache.entity-list.default.ProductCategoryMember.expireTime=3600000
> entitycache.entity-list.default.ProductCategoryMember.useSoftReference=true
> entitycache.entity-list.default.ProductCategoryMember.maxInMemory=5000
> entitycache.entity-list.default.ProductCategoryMember.maxSize=7500
> I analyzed the code of LRUMap and its usage in CacheLineTable and IMHO the
> bug is a missing synchonized in get():
> public CacheLine<V> get(Object key) {
> if (key == null) {
> if (Debug.verboseOn()) Debug.logVerbose("In CacheLineTable tried
> to get with null key, using NullObject" + this.cacheName, module);
> }
> return getNoCheck(key);
> }
> Since LRUMap extends LinkedHashMap, if you look at get method, it changes the
> state of the Map by calling e.recordAccess(this):
> public V get(Object key) {
> Entry<K,V> e = (Entry<K,V>)getEntry(key);
> if (e == null)
> return null;
> e.recordAccess(this);
> return e.value;
> }
> So the default of synchronization corrupts the state of LRUMap which grows
> indefinitely
> I will submit a patch for this on the trunk.
> Philippe
> www.ubik-ingenierie.com
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