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  1. Commons JCS
  2. JCS-144

BlockDiskCache hangs on SEVERE: Region [TMS] Failure getting from disk--IOException

    Details

    • Type: Bug
    • Status: Closed
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: jcs-2.0-beta-2
    • Fix Version/s: jcs-2.0-beta-2
    • Component/s: Indexed Disk Cache
    • Labels:
      None
    • Environment:
      version 1.7.0_75, vendor Oracle Corporation

      Description

      If I get a failure reading an object from cache, the thread locks, with following stack trace:
      "AWT-EventQueue-0" prio=6 tid=0x00000000112aa000 nid=0x1444 waiting on condition [0x0000000013dc9000]
      java.lang.Thread.State: WAITING (parking)
      at sun.misc.Unsafe.park(Native Method)

      • parking to wait for <0x00000007cbf84b00> (a java.util.concurrent.locks.ReentrantReadWriteLock$NonfairSync)
        at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:834)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:867)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1197)
        at java.util.concurrent.locks.ReentrantReadWriteLock$WriteLock.lock(ReentrantReadWriteLock.java:945)
        at org.apache.commons.jcs.auxiliary.disk.block.BlockDiskCache.reset(BlockDiskCache.java:643)
        at org.apache.commons.jcs.auxiliary.disk.block.BlockDiskCache.processGet(BlockDiskCache.java:343)
        at org.apache.commons.jcs.auxiliary.AbstractAuxiliaryCacheEventLogging.getWithEventLogging(AbstractAuxiliaryCacheEventLogging.java:109)
        at org.apache.commons.jcs.auxiliary.disk.AbstractDiskCache.doGet(AbstractDiskCache.java:771)
        at org.apache.commons.jcs.auxiliary.disk.AbstractDiskCache.get(AbstractDiskCache.java:279)
        at org.apache.commons.jcs.engine.control.CompositeCache.get(CompositeCache.java:550)
      • locked <0x00000007cbf62c00> (a org.apache.commons.jcs.engine.control.CompositeCache)
        at org.apache.commons.jcs.engine.control.CompositeCache.get(CompositeCache.java:455)
        at org.apache.commons.jcs.access.CacheAccess.getCacheElement(CacheAccess.java:125)

      Looing at the code in BlockDiskCache I see, that we first acquire read lock in processGet, and then try to acquire write lock in reset(). According to API spec: http://docs.oracle.com/javase/7/docs/api/java/util/concurrent/locks/ReentrantReadWriteLock.html

      It is unsupported to upgrade an lock from read to write ("Additionally, a writer can acquire the read lock, but not vice-versa").

      Either read lock should be dropped early on exception or different lock mechanism should be used

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            • Assignee:
              tv Thomas Vandahl
              Reporter:
              wiktorn Wiktor N
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              Dates

              • Created:
                Updated:
                Resolved: