narendly commented on a change in pull request #506: Increase parallelism for
ZkBucketDataAccessor
URL: https://github.com/apache/helix/pull/506#discussion_r334720366
##########
File path:
helix-core/src/main/java/org/apache/helix/manager/zk/ZkBucketDataAccessor.java
##########
@@ -85,103 +87,121 @@ public Object deserialize(byte[] data) throws
ZkMarshallingError {
return data;
}
});
- _zkBaseDataAccessor = new ZkBaseDataAccessor(_zkClient);
-
- // TODO: Optimize serialization with Jackson
- // TODO: Or use a better binary serialization protocol
- // TODO: Consider making this also binary
- // TODO: Consider an async write for the metadata as well
- _znRecordClient = SharedZkClientFactory.getInstance()
- .buildZkClient(new HelixZkClient.ZkConnectionConfig(zkAddr));
- _znRecordBaseDataAccessor = new ZkBaseDataAccessor<>(_znRecordClient);
- _znRecordClient.setZkSerializer(new ZNRecordSerializer());
-
+ _zkBaseDataAccessor = new ZkBaseDataAccessor<>(_zkClient);
_zkSerializer = new ZNRecordJacksonSerializer();
_bucketSize = bucketSize;
- _numVersions = numVersions;
+ _versionTTL = versionTTL;
}
/**
* Constructor that uses a default bucket size.
* @param zkAddr
*/
public ZkBucketDataAccessor(String zkAddr) {
- this(zkAddr, DEFAULT_BUCKET_SIZE, DEFAULT_NUM_VERSIONS);
+ this(zkAddr, DEFAULT_BUCKET_SIZE, DEFAULT_VERSION_TTL);
}
@Override
public <T extends HelixProperty> boolean compressedBucketWrite(String path,
T value)
throws IOException {
- // Take the ZNrecord and serialize it (get byte[])
+ final long timestamp = System.currentTimeMillis();
+
+ DataUpdater<byte[]> lastWriteVersionUpdater = dataInZk -> {
+ if (dataInZk == null || dataInZk.length == 0) {
+ // No last write version exists, so start with 0
+ return ("0_" + timestamp).getBytes();
Review comment:
Please see
https://github.com/apache/helix/wiki/Concurrency-and-Parallelism-for-BucketDataAccessor
for details.
Timestamp cannot be used for monotonically-increasing sequences because of
clock drift.
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