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https://issues.apache.org/jira/browse/BEAM-4049?focusedWorklogId=92090&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-92090
]
ASF GitHub Bot logged work on BEAM-4049:
----------------------------------------
Author: ASF GitHub Bot
Created on: 18/Apr/18 11:51
Start Date: 18/Apr/18 11:51
Worklog Time Spent: 10m
Work Description: echauchot commented on a change in pull request #5112:
[BEAM-4049] Improve CassandraIO write throughput by performing async queries
URL: https://github.com/apache/beam/pull/5112#discussion_r182354003
##########
File path:
sdks/java/io/cassandra/src/main/java/org/apache/beam/sdk/io/cassandra/CassandraServiceImpl.java
##########
@@ -351,33 +354,54 @@ public TokenRange(
*/
protected class WriterImpl<T> implements Writer<T> {
+ /**
+ * The threshold of 100 concurrent async queries is a heuristic commonly
used
+ * by the Apache Cassandra community. There is no real gain to expect in
tuning this value.
+ */
+ private static final int CONCURRENT_ASYNC_QUERIES = 100;
+
private final CassandraIO.Write<T> spec;
private final Cluster cluster;
private final Session session;
private final MappingManager mappingManager;
+ private List<ListenableFuture<Void>> writeFutures;
public WriterImpl(CassandraIO.Write<T> spec) {
this.spec = spec;
this.cluster = getCluster(spec.hosts(), spec.port(), spec.username(),
spec.password(),
spec.localDc(), spec.consistencyLevel());
this.session = cluster.connect(spec.keyspace());
this.mappingManager = new MappingManager(session);
+ this.writeFutures = Lists.newArrayList();
}
/**
* Write the entity to the Cassandra instance, using {@link Mapper}
obtained with the
- * {@link MappingManager}. This method use {@link Mapper#save(Object)}
method, which is
- * synchronous. It means the entity is guaranteed to be reliably committed
to Cassandra.
+ * {@link MappingManager}. This method use {@link
Mapper#saveAsync(Object)} method, which is
+ * asynchronous. Beam will wait for all futures to complete, to guarantee
all writes have
+ * succeeded.
*/
@Override
- public void write(T entity) {
+ public void write(T entity) throws ExecutionException,
InterruptedException {
Mapper<T> mapper = (Mapper<T>) mappingManager.mapper(entity.getClass());
- mapper.save(entity);
+ this.writeFutures.add(mapper.saveAsync(entity));
+ if (this.writeFutures.size() % CONCURRENT_ASYNC_QUERIES == 0) {
+ // We reached the max number of allowed in flight queries
+ LOG.info("Waiting for a batch of {} Cassandra writes to be
executed...",
+ CONCURRENT_ASYNC_QUERIES);
+ waitForFuturesToFinish();
Review comment:
Add a comment like "as stated in the CassandraService interface, write
methods needs to be synchronous, so blocks until all the asynchronous queries
are issued"
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Issue Time Tracking
-------------------
Worklog Id: (was: 92090)
Time Spent: 4h 40m (was: 4.5h)
> Improve write throughput of CassandraIO
> ---------------------------------------
>
> Key: BEAM-4049
> URL: https://issues.apache.org/jira/browse/BEAM-4049
> Project: Beam
> Issue Type: Improvement
> Components: io-java-cassandra
> Affects Versions: 2.4.0
> Reporter: Alexander Dejanovski
> Assignee: Alexander Dejanovski
> Priority: Major
> Labels: performance
> Time Spent: 4h 40m
> Remaining Estimate: 0h
>
> The CassandraIO currently uses the mapper to perform writes in a synchronous
> fashion.
> This implies that writes are serialized and is a very suboptimal way of
> writing to Cassandra.
> The IO should use the saveAsync() method instead of save() and should wait
> for completion each time 100 queries are in flight, in order to avoid
> overwhelming clusters.
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