[GitHub] keith-turner closed pull request #539: Fix WAL race condition between zookeeper and metadata table

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

keith-turner closed pull request #539: Fix WAL race condition between zookeeper and metadata table
URL: https://github.com/apache/accumulo/pull/539
 
 
   

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diff --git a/server/tserver/src/main/java/org/apache/accumulo/tserver/tablet/Tablet.java b/server/tserver/src/main/java/org/apache/accumulo/tserver/tablet/Tablet.java
index 1e0ffcc7b0..508e87ef52 100644
--- a/server/tserver/src/main/java/org/apache/accumulo/tserver/tablet/Tablet.java
+++ b/server/tserver/src/main/java/org/apache/accumulo/tserver/tablet/Tablet.java
@@ -2458,11 +2458,22 @@ public void importMapFiles(long tid, Map<FileRef,MapFileInfo> fileMap, boolean s
 
   private Set<DfsLogger> currentLogs = new HashSet<>();
 
-  public synchronized void removeInUseLogs(Set<DfsLogger> candidates) {
-    // remove logs related to minor compacting data
-    candidates.removeAll(otherLogs);
-    // remove logs related to tablets in memory data
-    candidates.removeAll(currentLogs);
+  public void removeInUseLogs(Set<DfsLogger> candidates) {
+    // This lock is held while clearing otherLogs and adding a minc file to metadata table. Not
+    // holding this lock leads to a small chance of data loss if tserver dies between clearing
+    // otherLogs and adding file to metadata table AND this method was called in the time between.
+    logLock.lock();
+    try {
+      // acquire locks in same order as other places in code to avoid deadlock
+      synchronized (this) {
+        // remove logs related to minor compacting data
+        candidates.removeAll(otherLogs);
+        // remove logs related to tablets in memory data
+        candidates.removeAll(currentLogs);
+      }
+    } finally {
+      logLock.unlock();
+    }
   }
 
   Set<String> beginClearingUnusedLogs() {


 

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