diff --git a/ci/jenkinsfile/milvus_build.groovy b/ci/jenkinsfile/milvus_build.groovy
index 99892c90ef..016acfdefa 100644
--- a/ci/jenkinsfile/milvus_build.groovy
+++ b/ci/jenkinsfile/milvus_build.groovy
@@ -1,5 +1,5 @@
 container('milvus-build-env') {
-    timeout(time: 20, unit: 'MINUTES') {
+    timeout(time: 30, unit: 'MINUTES') {
         gitlabCommitStatus(name: 'Build Engine') {
             dir ("milvus_engine") {
                 try {
@@ -17,4 +17,3 @@ container('milvus-build-env') {
         }
     }
 }
-
diff --git a/ci/jenkinsfile/milvus_build_no_ut.groovy b/ci/jenkinsfile/milvus_build_no_ut.groovy
index 6c30ce491c..f4e243f1cc 100644
--- a/ci/jenkinsfile/milvus_build_no_ut.groovy
+++ b/ci/jenkinsfile/milvus_build_no_ut.groovy
@@ -1,5 +1,5 @@
 container('milvus-build-env') {
-    timeout(time: 20, unit: 'MINUTES') {
+    timeout(time: 30, unit: 'MINUTES') {
         gitlabCommitStatus(name: 'Build Engine') {
             dir ("milvus_engine") {
                 try {
@@ -17,4 +17,3 @@ container('milvus-build-env') {
         }
     }
 }
-
diff --git a/cpp/CHANGELOG.md b/cpp/CHANGELOG.md
index 3ac9db25a1..812e62eb2d 100644
--- a/cpp/CHANGELOG.md
+++ b/cpp/CHANGELOG.md
@@ -17,6 +17,7 @@ Please mark all change in change log and use the ticket from JIRA.
 - MS-232 - Add MySQLMetaImpl::UpdateTableFilesToIndex and set maximum_memory to default if config value = 0
 - MS-233 - Remove mem manager log
 - MS-230 - Change parameter name: Maximum_memory to insert_buffer_size
+- MS-234 - Some case cause background merge thread stop
 
 ## Improvement
 - MS-156 - Add unittest for merge result functions
diff --git a/cpp/src/db/DBImpl.cpp b/cpp/src/db/DBImpl.cpp
index 6e4c49fc35..863f3db639 100644
--- a/cpp/src/db/DBImpl.cpp
+++ b/cpp/src/db/DBImpl.cpp
@@ -89,6 +89,7 @@ DBImpl::DBImpl(const Options& options)
     meta_ptr_ = DBMetaImplFactory::Build(options.meta, options.mode);
     mem_mgr_ = MemManagerFactory::Build(meta_ptr_, options_);
     if (options.mode != Options::MODE::READ_ONLY) {
+        ENGINE_LOG_INFO << "StartTimerTasks";
         StartTimerTasks();
     }
 }
@@ -389,10 +390,6 @@ Status DBImpl::BackgroundMergeFiles(const std::string& table_id) {
 }
 
 void DBImpl::BackgroundCompaction(std::set<std::string> table_ids) {
-//    static int b_count = 0;
-//    b_count++;
-//    std::cout << "BackgroundCompaction: " << b_count << std::endl;
-
     Status status;
     for (auto& table_id : table_ids) {
         status = BackgroundMergeFiles(table_id);
@@ -407,7 +404,6 @@ void DBImpl::BackgroundCompaction(std::set<std::string> table_ids) {
     int ttl = 1;
     if (options_.mode == Options::MODE::CLUSTER) {
         ttl = meta::D_SEC;
-//        ENGINE_LOG_DEBUG << "Server mode is cluster. Clean up files with ttl = " << std::to_string(ttl) << "seconds.";
     }
     meta_ptr_->CleanUpFilesWithTTL(ttl);
 }
@@ -540,7 +536,6 @@ void DBImpl::BackgroundBuildIndex() {
     meta_ptr_->FilesToIndex(to_index_files);
     Status status;
     for (auto& file : to_index_files) {
-        /* ENGINE_LOG_DEBUG << "Buiding index for " << file.location; */
         status = BuildIndex(file);
         if (!status.ok()) {
             ENGINE_LOG_ERROR << "Building index for " << file.id_ << " failed: " << status.ToString();
@@ -551,7 +546,6 @@ void DBImpl::BackgroundBuildIndex() {
             break;
         }
     }
-    /* ENGINE_LOG_DEBUG << "All Buiding index Done"; */
 }
 
 Status DBImpl::DropAll() {