YARN-5368. Memory leak in timeline server (Jonathan Eagles via Varun Saxena)

(cherry picked from commit 01aca54a22)

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-applicationhistoryservice/src/main/java/org/apache/hadoop/yarn/server/timeline/RollingLevelDBTimelineStore.java

@@ -275,9 +275,7 @@ public class RollingLevelDBTimelineStore extends AbstractService implements
     Path domainDBPath = new Path(dbPath, DOMAIN);
     Path starttimeDBPath = new Path(dbPath, STARTTIME);
     Path ownerDBPath = new Path(dbPath, OWNER);
-    FileSystem localFS = null;
-    try {
-      localFS = FileSystem.getLocal(conf);
+    try (FileSystem localFS = FileSystem.getLocal(conf)) {
       if (!localFS.exists(dbPath)) {
         if (!localFS.mkdirs(dbPath)) {
           throw new IOException("Couldn't create directory for leveldb "
@@ -306,8 +304,6 @@ public class RollingLevelDBTimelineStore extends AbstractService implements
         }
         localFS.setPermission(ownerDBPath, LEVELDB_DIR_UMASK);
       }
-    } finally {
-      IOUtils.cleanup(LOG, localFS);
     }
     options.maxOpenFiles(conf.getInt(
         TIMELINE_SERVICE_LEVELDB_MAX_OPEN_FILES,
@@ -408,19 +404,15 @@ public class RollingLevelDBTimelineStore extends AbstractService implements
         .add(writeReverseOrderedLong(revStartTime)).add(entityId)
         .getBytesForLookup();
 
-    DBIterator iterator = null;
-    try {
     DB db = entitydb.getDBForStartTime(revStartTime);
     if (db == null) {
       return null;
     }
-      iterator = db.iterator();
+    try (DBIterator iterator = db.iterator()) {
       iterator.seek(prefix);
 
       return getEntity(entityId, entityType, revStartTime, fields, iterator,
           prefix, prefix.length);
-    } finally {
-      IOUtils.cleanup(LOG, iterator);
     }
   }
 
@@ -533,8 +525,7 @@ public class RollingLevelDBTimelineStore extends AbstractService implements
                 o2.length);
           }
         });
-    DBIterator iterator = null;
-    try {
+
       // look up start times for the specified entities
       // skip entities with no start time
     for (String entityId : entityIds) {
@@ -582,7 +573,7 @@ public class RollingLevelDBTimelineStore extends AbstractService implements
         if (db == null) {
           continue;
         }
-          iterator = db.iterator();
+        try (DBIterator iterator = db.iterator()) {
           for (iterator.seek(first); entity.getEvents().size() < limit
               && iterator.hasNext(); iterator.next()) {
             byte[] key = iterator.peekNext().getKey();
@@ -599,8 +590,6 @@ public class RollingLevelDBTimelineStore extends AbstractService implements
           }
         }
       }
-    } finally {
-      IOUtils.cleanup(LOG, iterator);
     }
     return events;
   }
@@ -657,8 +646,6 @@ public class RollingLevelDBTimelineStore extends AbstractService implements
       Long limit, Long starttime, Long endtime, String fromId, Long fromTs,
       Collection<NameValuePair> secondaryFilters, EnumSet<Field> fields,
       CheckAcl checkAcl, boolean usingPrimaryFilter) throws IOException {
-    DBIterator iterator = null;
-    try {
     KeyBuilder kb = KeyBuilder.newInstance().add(base).add(entityType);
     // only db keys matching the prefix (base + entity type) will be parsed
     byte[] prefix = kb.getBytesForLookup();
@@ -716,7 +703,7 @@ public class RollingLevelDBTimelineStore extends AbstractService implements
 
     DB db = rollingdb.getDBForStartTime(firstStartTime);
     while (entities.getEntities().size() < limit && db != null) {
-        iterator = db.iterator();
+      try (DBIterator iterator = db.iterator()) {
         iterator.seek(first);
 
         // iterate until one of the following conditions is met: limit is
@@ -814,10 +801,8 @@ public class RollingLevelDBTimelineStore extends AbstractService implements
         }
         db = rollingdb.getPreviousDB(db);
       }
-      return entities;
-    } finally {
-      IOUtils.cleanup(LOG, iterator);
     }
+    return entities;
   }
 
   /**
@@ -1459,15 +1444,14 @@ public class RollingLevelDBTimelineStore extends AbstractService implements
     long startTimesCount = 0;
 
     WriteBatch writeBatch = null;
-    DBIterator iterator = null;
 
-    try {
-      writeBatch = starttimedb.createWriteBatch();
     ReadOptions readOptions = new ReadOptions();
     readOptions.fillCache(false);
-      iterator = starttimedb.iterator(readOptions);
+    try (DBIterator iterator = starttimedb.iterator(readOptions)) {
+
       // seek to the first start time entry
       iterator.seekToFirst();
+      writeBatch = starttimedb.createWriteBatch();
 
       // evaluate each start time entry to see if it needs to be evicted or not
       while (iterator.hasNext()) {
@@ -1513,7 +1497,6 @@ public class RollingLevelDBTimelineStore extends AbstractService implements
           + " start time entities earlier than " + minStartTime);
     } finally {
       IOUtils.cleanup(LOG, writeBatch);
-      IOUtils.cleanup(LOG, iterator);
     }
     return startTimesCount;
   }
@@ -1598,11 +1581,9 @@ public class RollingLevelDBTimelineStore extends AbstractService implements
   // TODO: make data retention work with the domain data as well
   @Override
   public void put(TimelineDomain domain) throws IOException {
-    WriteBatch domainWriteBatch = null;
-    WriteBatch ownerWriteBatch = null;
-    try {
-      domainWriteBatch = domaindb.createWriteBatch();
-      ownerWriteBatch = ownerdb.createWriteBatch();
+    try (WriteBatch domainWriteBatch = domaindb.createWriteBatch();
+         WriteBatch ownerWriteBatch = ownerdb.createWriteBatch();) {
+
       if (domain.getId() == null || domain.getId().length() == 0) {
         throw new IllegalArgumentException("Domain doesn't have an ID");
       }
@@ -1682,9 +1663,6 @@ public class RollingLevelDBTimelineStore extends AbstractService implements
       ownerWriteBatch.put(ownerLookupEntryKey, timestamps);
       domaindb.write(domainWriteBatch);
       ownerdb.write(ownerWriteBatch);
-    } finally {
-      IOUtils.cleanup(LOG, domainWriteBatch);
-      IOUtils.cleanup(LOG, ownerWriteBatch);
     }
   }
 
@@ -1709,26 +1687,21 @@ public class RollingLevelDBTimelineStore extends AbstractService implements
 
   @Override
   public TimelineDomain getDomain(String domainId) throws IOException {
-    DBIterator iterator = null;
-    try {
+    try (DBIterator iterator = domaindb.iterator()) {
       byte[] prefix = KeyBuilder.newInstance().add(domainId)
           .getBytesForLookup();
-      iterator = domaindb.iterator();
       iterator.seek(prefix);
       return getTimelineDomain(iterator, domainId, prefix);
-    } finally {
-      IOUtils.cleanup(LOG, iterator);
     }
   }
 
   @Override
   public TimelineDomains getDomains(String owner) throws IOException {
-    DBIterator iterator = null;
-    try {
+    try (DBIterator iterator = ownerdb.iterator()) {
       byte[] prefix = KeyBuilder.newInstance().add(owner).getBytesForLookup();
+      iterator.seek(prefix);
       List<TimelineDomain> domains = new ArrayList<TimelineDomain>();
-      for (iterator = ownerdb.iterator(), iterator.seek(prefix); iterator
-          .hasNext();) {
+      while (iterator.hasNext()) {
         byte[] key = iterator.peekNext().getKey();
         if (!prefixMatches(prefix, prefix.length, key)) {
           break;
@@ -1761,8 +1734,6 @@ public class RollingLevelDBTimelineStore extends AbstractService implements
       TimelineDomains domainsToReturn = new TimelineDomains();
       domainsToReturn.addDomains(domains);
       return domainsToReturn;
-    } finally {
-      IOUtils.cleanup(LOG, iterator);
     }
   }