org.apache.cassandra.db.compaction
Class ParallelCompactionIterable

java.lang.Object
  org.apache.cassandra.db.compaction.AbstractCompactionIterable
      org.apache.cassandra.db.compaction.ParallelCompactionIterable

All Implemented Interfaces:

java.lang.Iterable<AbstractCompactedRow>, CompactionInfo.Holder

public class ParallelCompactionIterable
extends AbstractCompactionIterable

A class to run compaction taking advantage of multiple-core processes: One Deserializer thread per input sstable performs read + deserialize (a row at a time). The resulting ColumnFamilies are added to a queue, which is fed to the merge Reducer. The merge Reducer creates MergeTasks on a thread-per-core Executor, and returns AsyncPrecompactedRow objects. The main complication is in handling larger-than-memory rows. When one is encountered, no further deserialization is done until that row is merged and written -- creating a pipeline stall, as it were. Thus, this is intended to be useful with mostly-in-memory row sizes, but preserves correctness in the face of occasional exceptions.

Field Summary

Fields inherited from class org.apache.cassandra.db.compaction.AbstractCompactionIterable

bytesRead, controller, throttle, totalBytes, type

Constructor Summary

	ParallelCompactionIterable(OperationType type, java.lang.Iterable<SSTableReader> sstables, CompactionController controller)
	ParallelCompactionIterable(OperationType type, java.lang.Iterable<SSTableReader> sstables, CompactionController controller, int maxInMemorySize)
protected	ParallelCompactionIterable(OperationType type, java.util.List<SSTableScanner> scanners, CompactionController controller, int maxInMemorySize)

Method Summary

CloseableIterator<AbstractCompactedRow>

iterator()

Methods inherited from class org.apache.cassandra.db.compaction.AbstractCompactionIterable

getCompactionInfo, getScanners

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ParallelCompactionIterable

public ParallelCompactionIterable(OperationType type,
                                  java.lang.Iterable<SSTableReader> sstables,
                                  CompactionController controller)
                           throws java.io.IOException

Throws:

java.io.IOException

ParallelCompactionIterable

public ParallelCompactionIterable(OperationType type,
                                  java.lang.Iterable<SSTableReader> sstables,
                                  CompactionController controller,
                                  int maxInMemorySize)
                           throws java.io.IOException

Throws:

java.io.IOException

ParallelCompactionIterable

protected ParallelCompactionIterable(OperationType type,
                                     java.util.List<SSTableScanner> scanners,
                                     CompactionController controller,
                                     int maxInMemorySize)

Method Detail

iterator

public CloseableIterator<AbstractCompactedRow> iterator()

Specified by:

iterator in interface java.lang.Iterable<AbstractCompactedRow>

Specified by:

iterator in class AbstractCompactionIterable