记一次死锁问题的排查和解决

Found one Java-level deadlock:
=============================
"mondrian.rolap.RolapResultShepherd$executor_160":
  waiting to lock monitor 0x0000000043b2bf70 (object 0x0000000702080db0, a mondrian.rolap.MemberCacheHelper),
  which is held by "mondrian.rolap.RolapResultShepherd$executor_152"
"mondrian.rolap.RolapResultShepherd$executor_152":
  waiting to lock monitor 0x00007f4e6c0751c8 (object 0x0000000702081270, a mondrian.rolap.MemberCacheHelper),
  which is held by "http-8182-11"
"http-8182-11":
  waiting to lock monitor 0x0000000043b2bf70 (object 0x0000000702080db0, a mondrian.rolap.MemberCacheHelper),
  which is held by "mondrian.rolap.RolapResultShepherd$executor_152"

at mondrian.rolap.SmartMemberReader.flushCacheSimple(SmartMemberReader.java:577)
        - waiting to lock <0x00000007020a8990> (a mondrian.rolap.MemberCacheHelper)
        at mondrian.rolap.RolapCubeHierarchy$CacheRolapCubeHierarchyMemberReader.flushCacheSimple(RolapCubeHierarchy.java:883)
        at mondrian.rolap.RolapCubeHierarchy.flushCacheSimple(RolapCubeHierarchy.java:458)
        at mondrian.rolap.MemberCacheHelper.flushCache(MemberCacheHelper.java:166)
        - locked <0x00000007020a8e50> (a mondrian.rolap.MemberCacheHelper)
        at mondrian.rolap.RolapCubeHierarchy$CacheRolapCubeHierarchyMemberReader.flushCache(RolapCubeHierarchy.java:878)
        at mondrian.rolap.RolapCubeHierarchy.flushCache(RolapCubeHierarchy.java:451)

         @Override
        public void flushCache(){
            super.flushCache();
            rolapCubeCacheHelper.flushCache();
        }

     public void flushCache(){
      synchronized( cacheHelper){
            cacheHelper .flushCache();
     }
    }

     // Must sync here because we want the three maps to be modified together.
    public synchronized void flushCache() {
        mapMemberToChildren.clear();
        mapKeyToMember.clear();
        mapLevelToMembers.clear();
        
        if (rolapHierarchy instanceof RolapCubeHierarchy){
             ((RolapCubeHierarchy)rolapHierarchy ).flushCacheSimple();
        }
        // We also need to clear the approxRowCount of each level.
        for (Level level : rolapHierarchy.getLevels()) {
            ((RolapLevel)level ).setApproxRowCount(Integer. MIN_VALUE);
        }
    }

     public void flushCacheSimple(){
           super.flushCacheSimple();
           rolapCubeCacheHelper.flushCacheSimple();
        }

    public void flushCacheSimple(){
     synchronized(cacheHelper){
           cacheHelper.flushCacheSimple();
     }
    }

    public synchronized void flushCacheSimple() {
        mapMemberToChildren.clear();
        mapKeyToMember.clear();
        mapLevelToMembers.clear();
        // We also need to clear the approxRowCount of each level.
        for (Level level : rolapHierarchy.getLevels()) {
            ((RolapLevel)level).setApproxRowCount(Integer.MIN_VALUE);
        }
    }