[GitHub] [incubator-doris] weizuo93 commented on a change in pull request #4373: [Optimize]Optimize the disk selection strategy on BE for tablet creation

[GitBox <gi...@apache.org>]

weizuo93 commented on a change in pull request #4373:
URL: https://github.com/apache/incubator-doris/pull/4373#discussion_r475558052



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File path: be/src/olap/storage_engine.cpp
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@@ -428,6 +428,18 @@ std::vector<DataDir*> StorageEngine::get_stores_for_create_tablet(
     std::random_device rd;
     srand(rd());
     std::random_shuffle(stores.begin(), stores.end());
+    // Two random choices
+    for (int i = 0; i < stores.size(); i++) {
+        int j = i + 1;
+        if (j < stores.size()) {
+            if (stores[i]->tablet_set().size() > stores[j]->tablet_set().size()) {
+                std::swap(stores[i], stores[j]);
+            }
+            std::random_shuffle(stores.begin() + j, stores.end());

Review comment:
       @chaoyli 
   The purpose of the this random_shuffle is that:
          If it failed to create tablet on the first disk selected using "two random choices", it is necessary to select another disk from the remaining disks to create the tablet by using "two random choices" again. This random_shuffle is the beginning of the next "two random choices".




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