[incubator-doris] branch master updated: [Optimize][Clone] Take version count into consideration when choosing src replica for clone task (#6513)

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morningman pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/incubator-doris.git


The following commit(s) were added to refs/heads/master by this push:
     new d5d8316  [Optimize][Clone] Take version count into consideration when choosing src replica for clone task (#6513)
d5d8316 is described below

commit d5d8316ff3c89febd1e7ba44e9b219ccf306c8d8
Author: weizuo93 <we...@apache.org>
AuthorDate: Mon Aug 30 18:52:41 2021 +0800

    [Optimize][Clone] Take version count into consideration when choosing src replica for clone task (#6513)
    
    Fix #6512
    
    If there is missing replica for a tablet, clone task will be executed to restore missing replica from a healthy replica. Src replica selector will randomly choose a healthy replica as src replica.
    
    It's better to choose the health replica with min version count as src replica so that it could avoid repetitive compaction task. In addition, replica with less version count is good for query performance.
---
 .../org/apache/doris/clone/TabletSchedCtx.java     | 24 +++++++++++++++++++---
 1 file changed, 21 insertions(+), 3 deletions(-)

diff --git a/fe/fe-core/src/main/java/org/apache/doris/clone/TabletSchedCtx.java b/fe/fe-core/src/main/java/org/apache/doris/clone/TabletSchedCtx.java
index fd36689..8e3ab51 100644
--- a/fe/fe-core/src/main/java/org/apache/doris/clone/TabletSchedCtx.java
+++ b/fe/fe-core/src/main/java/org/apache/doris/clone/TabletSchedCtx.java
@@ -489,8 +489,10 @@ public class TabletSchedCtx implements Comparable<TabletSchedCtx> {
         if (candidates.isEmpty()) {
             throw new SchedException(Status.UNRECOVERABLE, "unable to find source replica");
         }
-        
+
         // choose a replica which slot is available from candidates.
+        long minVersionCount = Long.MAX_VALUE;
+        boolean findSrcReplica = false;
         for (Replica srcReplica : candidates) {
             PathSlot slot = backendsWorkingSlots.get(srcReplica.getBackendId());
             if (slot == null) {
@@ -499,10 +501,26 @@ public class TabletSchedCtx implements Comparable<TabletSchedCtx> {
             
             long srcPathHash = slot.takeSlot(srcReplica.getPathHash());
             if (srcPathHash != -1) {
-                setSrc(srcReplica);
-                return;
+                if (!findSrcReplica) {
+                    // version count is set by report process, so it may not be set yet and default value is -1.
+                    // so we need to check it.
+                    minVersionCount = srcReplica.getVersionCount() == -1 ? Long.MAX_VALUE : srcReplica.getVersionCount();
+                    setSrc(srcReplica);
+                    findSrcReplica = true;
+                } else {
+                    long curVerCount = srcReplica.getVersionCount() == -1 ? Long.MAX_VALUE : srcReplica.getVersionCount();
+                    if (curVerCount < minVersionCount) {
+                        minVersionCount = curVerCount;
+                        setSrc(srcReplica);
+                        findSrcReplica = true;
+                    }
+                }
             }
         }
+
+        if (findSrcReplica) {
+            return;
+        }
         
         throw new SchedException(Status.SCHEDULE_FAILED, "unable to find source slot");
     }

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