baohe-zhang commented on a change in pull request #29425:
URL: https://github.com/apache/spark/pull/29425#discussion_r481478177
##########
File path:
common/kvstore/src/main/java/org/apache/spark/util/kvstore/LevelDB.java
##########
@@ -164,35 +165,39 @@ public void writeAll(List<?> values) throws Exception {
Preconditions.checkArgument(values != null && !values.isEmpty(),
"Non-empty values required.");
- // Group by class, in case there are values from different classes in the
values
+ // Group by class, in case there are values from different classes in the
values.
// Typical usecase is for this to be a single class.
// A NullPointerException will be thrown if values contain null object.
for (Map.Entry<? extends Class<?>, ? extends List<?>> entry :
values.stream().collect(Collectors.groupingBy(Object::getClass)).entrySet()) {
-
- final Iterator<?> valueIter = entry.getValue().iterator();
- final Iterator<byte[]> serializedValueIter;
-
- // Deserialize outside synchronized block
- List<byte[]> list = new ArrayList<>(entry.getValue().size());
- for (Object value : values) {
- list.add(serializer.serialize(value));
- }
- serializedValueIter = list.iterator();
-
final Class<?> klass = entry.getKey();
- final LevelDBTypeInfo ti = getTypeInfo(klass);
- synchronized (ti) {
- final LevelDBTypeInfo.Index naturalIndex = ti.naturalIndex();
- final Collection<LevelDBTypeInfo.Index> indices = ti.indices();
+ // Partition the value list to a set of the 128-values batches. It can
reduce the
+ // memory pressure caused by serialization and give fairness to other
writing threads
+ // when writing a very large list.
+ for (List<?> batchList : Iterables.partition(entry.getValue(), 128)) {
+ final Iterator<?> valueIter = batchList.iterator();
+ final Iterator<byte[]> serializedValueIter;
+
+ // Deserialize outside synchronized block
+ List<byte[]> serializedValueList = new ArrayList<>(batchList.size());
+ for (Object value : batchList) {
+ serializedValueList.add(serializer.serialize(value));
+ }
+ serializedValueIter = serializedValueList.iterator();
+
+ final LevelDBTypeInfo ti = getTypeInfo(klass);
+ synchronized (ti) {
+ final LevelDBTypeInfo.Index naturalIndex = ti.naturalIndex();
+ final Collection<LevelDBTypeInfo.Index> indices = ti.indices();
- try (WriteBatch batch = db().createWriteBatch()) {
while (valueIter.hasNext()) {
- updateBatch(batch, valueIter.next(), serializedValueIter.next(),
klass,
- naturalIndex, indices);
+ try (WriteBatch batch = db().createWriteBatch()) {
+ updateBatch(batch, valueIter.next(), serializedValueIter.next(),
klass,
+ naturalIndex, indices);
+ db().write(batch);
Review comment:
Hi @HeartSaVioR , I fixed the bug by using a hashmap to store and update
the <countKey, delta> pair in a batch and use the information in that hashmap
to update the count right before calling db.write(batch). I updated the test
case to cover the count update issue. I also ran benchmark tests for writeAll
and put the result in the description section of this PR.
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