baohe-zhang commented on a change in pull request #29425:
URL: https://github.com/apache/spark/pull/29425#discussion_r481479994
##########
File path:
common/kvstore/src/main/java/org/apache/spark/util/kvstore/LevelDB.java
##########
@@ -164,35 +166,44 @@ 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 large value list to a set of smaller batches, to reduce
the memory
+ // pressure caused by serialization and give fairness to other writing
threads.
+ for (List<?> batchList : Iterables.partition(entry.getValue(), 128)) {
+ final Iterator<?> valueIter = batchList.iterator();
+ final Iterator<byte[]> serializedValueIter;
- try (WriteBatch batch = db().createWriteBatch()) {
- while (valueIter.hasNext()) {
- updateBatch(batch, valueIter.next(), serializedValueIter.next(),
klass,
- naturalIndex, indices);
+ // 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()) {
+ // A hash map to update the delta of each countKey, wrap countKey
with type byte[]
+ // as ByteBuffer because ByteBuffer is comparable.
+ Map<ByteBuffer, Long> counts = new HashMap<>();
+ while (valueIter.hasNext()) {
+ updateBatch(batch, valueIter.next(), serializedValueIter.next(),
klass,
+ naturalIndex, indices, counts);
+ }
+ for (Map.Entry<ByteBuffer, Long> countEntry : counts.entrySet()) {
+ naturalIndex.updateCount(batch, countEntry.getKey().array(),
countEntry.getValue());
Review comment:
@HeartSaVioR Here I use **naturalIndex.updateCount()** to put the count
information of all indexes to the batch. When implementing this I found we can
lift the method **updateCount()** and **long getCount(byte[] key)** from
LevelDBTypeInfo.Index to LevelDBTypeInfo, as these methods are not accessing
any member of LevelDBTypeInfo.Index. Doing that would allow us to call
**ti.updateCount()** to update count for all indexes, which would make more
sense. However, it's totally optional.
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