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https://issues.apache.org/jira/browse/JCS-73?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13139697#comment-13139697
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Thomas Vandahl commented on JCS-73:
-----------------------------------
The IndexedDiskCache has been modified to use NIO to resolve concurrency
issues. Could you please test with the latest trunk?
> concurrent cache access causes values loss
> ------------------------------------------
>
> Key: JCS-73
> URL: https://issues.apache.org/jira/browse/JCS-73
> Project: JCS
> Issue Type: Bug
> Components: Indexed Disk Cache
> Affects Versions: jcs-1.3
> Reporter: Alexander Kleymenov
> Assignee: Aaron Smuts
>
> The following groovy code demonstrates the problem: several threads write to
> the cache and try to read previously written values. Sometimes just written
> values can't be retrieved. In this case, subsequent tries can get the value,
> but not always.
> {code}
> cache = org.apache.jcs.JCS.getInstance("cache")
> group = "group"
> worker = {
> def name = Thread.currentThread().name
> 10000.times { idx ->
> if (idx) {
> // get previously stored value
> def res = cache.getFromGroup(idx-1, group)
> if (!res) {
> // null value got inspite of the fact it was placed in cache!
> println "ERROR: for ${idx} in " + name
> // try to get the value again:
> def n = 5
> while (n-- > 0) {
> res = cache.getFromGroup(idx-1, group)
> if (res) {
> // the value finally appeared in cache
> println "ERROR FIXED for ${idx}: ${res} " + name
> break
> }
> println "ERROR STILL PERSISTS for ${idx} in " + name
> Thread.sleep(1000)
> }
> }
> }
> // put value in the cache
> cache.putInGroup(idx, group, [value:[a:1, b:2, c:3], aux:[1:'a',
> 2:'b', 3:'c', t:name]])
> if (!(idx % 10000)) {
> println name+" "+idx
> }
> }
> }
> Thread.start worker
> Thread.start worker
> Thread.start worker
> Thread.start worker
> Thread.start worker
> Thread.start worker
> Thread.start worker
> Thread.start worker
> {code}
> Cache configuration:
> {code}
> jcs.default=CACHE
> jcs.default.cacheattributes=org.apache.jcs.engine.CompositeCacheAttributes
> jcs.default.cacheattributes.MaxObjects=-1
> jcs.default.cacheattributes.MemoryCacheName=org.apache.jcs.engine.memory.lru.LRUMemoryCache
> jcs.default.cacheattributes.DiskUsagePatternName=UPDATE
> jcs.default.cacheattributes.UseMemoryShrinker=true
> jcs.default.cacheattributes.MaxMemoryIdleTimeSeconds=10
> jcs.default.cacheattributes.ShrinkerIntervalSeconds=10
> jcs.default.elementattributes=org.apache.jcs.engine.ElementAttributes
> jcs.default.elementattributes.IsRemote=false
> jcs.default.elementattributes.IsLateral=false
> jcs.default.elementattributes.IsSpool=true
> jcs.default.elementattributes.IsEternal=true
> jcs.auxiliary.CACHE=org.apache.jcs.auxiliary.disk.indexed.IndexedDiskCacheFactory
> jcs.auxiliary.CACHE.attributes=org.apache.jcs.auxiliary.disk.indexed.IndexedDiskCacheAttributes
> jcs.auxiliary.CACHE.attributes.DiskPath=./cache
> jcs.auxiliary.CACHE.attributes.MaxPurgatorySize=-1
> jcs.auxiliary.CACHE.attributes.MaxKeySize=-1
> jcs.auxiliary.CACHE.attributes.MaxRecycleBinSize=500
> jcs.auxiliary.CACHE.attributes.ShutdownSpoolTimeLimit=60
> jcs.auxiliary.CACHE.attributes.OptimizeAtRemoveCount=30000
> jcs.auxiliary.CACHE.attributes.OptimizeOnShutdown=true
> jcs.auxiliary.CACHE.attributes.EventQueueType=SINGLE
> {code}
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