diff --git a/spark-on-angel/graph/src/main/scala/com/tencent/angel/graph/community/copra/COPRAGraphPartition.scala b/spark-on-angel/graph/src/main/scala/com/tencent/angel/graph/community/copra/COPRAGraphPartition.scala
index 6c7cca172..1e5ef1064 100644
--- a/spark-on-angel/graph/src/main/scala/com/tencent/angel/graph/community/copra/COPRAGraphPartition.scala
+++ b/spark-on-angel/graph/src/main/scala/com/tencent/angel/graph/community/copra/COPRAGraphPartition.scala
@@ -17,10 +17,11 @@
 package com.tencent.angel.graph.community.copra
 
 
+import com.tencent.angel.graph.psf.triangle.NeighborsFloatAttrsElement
 import it.unimi.dsi.fastutil.floats.FloatArrayList
 import it.unimi.dsi.fastutil.ints.IntArrayList
 import it.unimi.dsi.fastutil.longs.{Long2ObjectOpenHashMap, LongArrayList}
-import com.tencent.angel.graph.psf.triangle.NeighborsFloatAttrsElement
+
 import scala.collection.mutable
 import scala.collection.mutable.ArrayBuffer
 import scala.util.Random
@@ -38,8 +39,9 @@ class COPRAGraphPartition(index: Int,
   def analysis(): Int = neighbors.length
 
   def initMsgs(model: COPRAPSModel): Unit = {
-    keys.sliding(batchSize, batchSize).foreach {partKeys =>
-      initPartMsgs(partKeys, model)}
+    keys.sliding(batchSize, batchSize).foreach { partKeys =>
+      initPartMsgs(partKeys, model)
+    }
   }
 
   def initPartMsgs(partKeys: Array[Long], model: COPRAPSModel): Unit = {
@@ -54,7 +56,7 @@ class COPRAGraphPartition(index: Int,
     println(s"partition $index: ---------- iteration $iteration starts ----------")
     keys.indices.sliding(batchSize, batchSize).foreach { nodesIndex =>
       val beforeCalcPullNodesTs = System.currentTimeMillis()
-      val pullNodes = neighbors.slice(indptr(nodesIndex.head), indptr(nodesIndex.last+1)).distinct
+      val pullNodes = neighbors.slice(indptr(nodesIndex.head), indptr(nodesIndex.last + 1)).distinct
       println(s"partition $index: calculating pull nodes cost ${System.currentTimeMillis() - beforeCalcPullNodesTs} ms")
 
       val beforePullCoeTs = System.currentTimeMillis()
@@ -101,17 +103,19 @@ class COPRAGraphPartition(index: Int,
     while (j < indptr(idx + 1)) {
       assert(comInMsgs.containsKey(neighbors(j)), s"Key ${neighbors(j)} is not in the keySet of comInMsgs.")
       val comGet = comInMsgs.get(neighbors(j))
-      val neis = comGet.getNeighborIds
-      val coes = comGet.getAttrs
-      var x = 0
-      while (x < comGet.getNodesNum) {
-        val label = neis(x)
-        val coe = coes(x)
-        val t = temp.getOrElse(label, 0f)
-        temp += ((label, t + coe * weights(j)))
-        x += 1
+      if (comGet != null) {
+        val neis = comGet.getNeighborIds
+        val coes = comGet.getAttrs
+        var x = 0
+        while (x < comGet.getNodesNum) {
+          val label = neis(x)
+          val coe = coes(x)
+          val t = temp.getOrElse(label, 0f)
+          temp += ((label, t + coe * weights(j)))
+          x += 1
+        }
+        j += 1
       }
-      j += 1
     }
     //    temp.remove(-1)
     if (temp.isEmpty) {
@@ -127,7 +131,7 @@ class COPRAGraphPartition(index: Int,
       }
       // normalize
       val norm = newAttr.values.sum
-      newAttr.map { case (node, coe) => (node, coe / norm)}.toArray
+      newAttr.map { case (node, coe) => (node, coe / norm) }.toArray
     }
   }
 
@@ -143,7 +147,7 @@ object COPRAGraphPartition {
     val indptr = new IntArrayList()
     val keys = new LongArrayList()
     val neighbors = new LongArrayList()
-    val keyLabels = ArrayBuffer[Array[(Long,Float)]]()
+    val keyLabels = ArrayBuffer[Array[(Long, Float)]]()
     val weights = new FloatArrayList()
 
     indptr.add(0)
@@ -165,7 +169,7 @@ object COPRAGraphPartition {
     val neighborsArray = neighbors.toLongArray()
     val indicesArray = keysArray.union(neighborsArray).distinct
 
-    new COPRAGraphPartition(index, numMaxCommunities,preserveRate,
+    new COPRAGraphPartition(index, numMaxCommunities, preserveRate,
       keysArray,
       indptr.toIntArray(),
       neighborsArray,