[iotdb] branch master updated: [IOTDB-4636] Add check to avoid flush empty chunk group (#7635)

[qiaojialin]

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qiaojialin pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/iotdb.git


The following commit(s) were added to refs/heads/master by this push:
     new 08b6c1514b [IOTDB-4636] Add check to avoid flush empty chunk group 
(#7635)
08b6c1514b is described below

commit 08b6c1514bb880b40ab87557462d5663ef455dba
Author: Haonan <hhao...@outlook.com>
AuthorDate: Tue Oct 18 10:22:22 2022 +0800

    [IOTDB-4636] Add check to avoid flush empty chunk group (#7635)
---
 .../org/apache/iotdb/db/engine/flush/MemTableFlushTask.java    | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git 
a/server/src/main/java/org/apache/iotdb/db/engine/flush/MemTableFlushTask.java 
b/server/src/main/java/org/apache/iotdb/db/engine/flush/MemTableFlushTask.java
index a86380749d..2653d67eac 100644
--- 
a/server/src/main/java/org/apache/iotdb/db/engine/flush/MemTableFlushTask.java
+++ 
b/server/src/main/java/org/apache/iotdb/db/engine/flush/MemTableFlushTask.java
@@ -122,14 +122,20 @@ public class MemTableFlushTask {
     // sort the IDeviceID in lexicographical order
     deviceIDList.sort(Comparator.comparing(IDeviceID::toStringID));
     for (IDeviceID deviceID : deviceIDList) {
-      encodingTaskQueue.put(new StartFlushGroupIOTask(deviceID.toStringID()));
-
       final Map<String, IWritableMemChunk> value = 
memTableMap.get(deviceID).getMemChunkMap();
+      // skip the empty device/chunk group
+      if (memTableMap.get(deviceID).count() == 0 || value.isEmpty()) {
+        continue;
+      }
+      encodingTaskQueue.put(new StartFlushGroupIOTask(deviceID.toStringID()));
       List<String> seriesInOrder = new ArrayList<>(value.keySet());
       seriesInOrder.sort((String::compareTo));
       for (String seriesId : seriesInOrder) {
         long startTime = System.currentTimeMillis();
         IWritableMemChunk series = value.get(seriesId);
+        if (series.count() == 0) {
+          continue;
+        }
         /*
          * sort task (first task of flush pipeline)
          */