@After
  public void tearDown() {
    CacheObserverHolder.setInstance(null);

    DiskStoreImpl.SET_IGNORE_PREALLOCATE = false;
    LocalRegion.ISSUE_CALLBACKS_TO_CACHE_OBSERVER = false;

    cache.close();
  }
This is a bugtest for bug 37500.

<p>
TRAC #37500: A DiskAccessException brings cache server to a stall

<pre>
com.gemstone.gemfire.cache.DiskAccessException:  Unable to get free space for creating an oplog after waiting for 20 seconds
    at com.gemstone.gemfire.internal.cache.ComplexDiskRegion.getNextDir(ComplexDiskRegion.java:150)
    at com.gemstone.gemfire.internal.cache.Oplog.switchOpLog(Oplog.java:2020)
    at com.gemstone.gemfire.internal.cache.Oplog.basicModify(Oplog.java:2423)
    at com.gemstone.gemfire.internal.cache.Oplog.modify(Oplog.java:2339)
    at com.gemstone.gemfire.internal.cache.DiskRegion.put(DiskRegion.java:321)
    at com.gemstone.gemfire.internal.cache.DiskEntry$Helper.writeToDisk(DiskEntry.java:362)
    at com.gemstone.gemfire.internal.cache.DiskEntry$Helper.overflowToDisk(DiskEntry.java:532)
    at com.gemstone.gemfire.internal.cache.AbstractLRURegionMap.evictEntry(AbstractLRURegionMap.java:164)
    at com.gemstone.gemfire.internal.cache.AbstractLRURegionMap.lruUpdateCallback(AbstractLRURegionMap.java:240)
    at com.gemstone.gemfire.internal.cache.AbstractRegionMap.basicPut(AbstractRegionMap.java:928)
    at com.gemstone.gemfire.internal.cache.LocalRegion.virtualPut(LocalRegion.java:3605)
    at com.gemstone.gemfire.internal.cache.DistributedRegion.virtualPut(DistributedRegion.java:151)
    at com.gemstone.gemfire.internal.cache.LocalRegion.basicUpdate(LocalRegion.java:3591)
    at com.gemstone.gemfire.internal.cache.AbstractUpdateOperation.doPutOrCreate(AbstractUpdateOperation.java:100)
    at com.gemstone.gemfire.internal.cache.AbstractUpdateOperation$AbstractUpdateMessage.basicOperateOnRegion(AbstractUpdateOperation.java:171)
    at com.gemstone.gemfire.internal.cache.AbstractUpdateOperation$AbstractUpdateMessage.operateOnRegion(AbstractUpdateOperation.java:154)
    at com.gemstone.gemfire.internal.cache.DistributedCacheOperation$CacheOperationMessage.basicProcess(DistributedCacheOperation.java:487)
    at com.gemstone.gemfire.internal.cache.DistributedCacheOperation$CacheOperationMessage.process(DistributedCacheOperation.java:404)
    at com.gemstone.gemfire.distributed.internal.DistributionMessage.scheduleAction(DistributionMessage.java:242)
    at com.gemstone.gemfire.distributed.internal.DistributionMessage.schedule(DistributionMessage.java:287)
    at com.gemstone.gemfire.distributed.internal.DistributionManager.scheduleIncomingMessage(DistributionManager.java:2732)
    at com.gemstone.gemfire.distributed.internal.DistributionManager.handleIncomingDMsg(DistributionManager.java:2424)
    at com.gemstone.gemfire.distributed.internal.DistributionManager$MyListener.messageReceived(DistributionManager.java:3585)
    at com.gemstone.gemfire.distributed.internal.membership.jgroup.JGroupMembershipManager.processMessage(JGroupMembershipManager.java:1349)
    at com.gemstone.gemfire.distributed.internal.membership.jgroup.JGroupMembershipManager.handleOrDeferMessage(JGroupMembershipManager.java:1289)
    at com.gemstone.gemfire.distributed.internal.membership.jgroup.JGroupMembershipManager$MyDCReceiver.messageReceived(JGroupMembershipManager.java:449)
    at com.gemstone.gemfire.distributed.internal.direct.DirectChannel.receive(DirectChannel.java:535)
    at com.gemstone.gemfire.internal.tcp.TCPConduit.messageReceived(TCPConduit.java:483)
    at com.gemstone.gemfire.internal.tcp.Connection.dispatchMessage(Connection.java:3026)
    at com.gemstone.gemfire.internal.tcp.Connection.processNIOBuffer(Connection.java:2861)
    at com.gemstone.gemfire.internal.tcp.Connection.runNioReader(Connection.java:1332)
    at com.gemstone.gemfire.internal.tcp.Connection.run(Connection.java:1257)
    at java.lang.Thread.run(Thread.java:595)
</pre>
geode-core/src/integrationTest/java/org/apache/geode/internal/cache/DiskAccessExceptionDisablesServerRegressionTest.java