Example usage for java.util.concurrent ConcurrentLinkedQueue ConcurrentLinkedQueue

Introduction

In this page you can find the example usage for java.util.concurrent ConcurrentLinkedQueue ConcurrentLinkedQueue.

Prototype

public ConcurrentLinkedQueue(Collection<? extends E> c) 

Source Link

Document

Creates a ConcurrentLinkedQueue initially containing the elements of the given collection, added in traversal order of the collection's iterator.

Usage

From source file:org.apache.giraph.worker.BspServiceSource.java

/**
 * Load saved partitions in multiple threads.
 * @param superstep superstep to load/*w ww .  j av  a  2s.  co  m*/
 * @param partitions list of partitions to load
 */
private void loadCheckpointVertices(final long superstep, List<Integer> partitions) {
    int numThreads = Math.min(GiraphConstants.NUM_CHECKPOINT_IO_THREADS.get(getConfiguration()),
            partitions.size());

    final Queue<Integer> partitionIdQueue = new ConcurrentLinkedQueue<>(partitions);

    final CompressionCodec codec = new CompressionCodecFactory(getConfiguration())
            .getCodec(new Path(GiraphConstants.CHECKPOINT_COMPRESSION_CODEC.get(getConfiguration())));

    long t0 = System.currentTimeMillis();

    CallableFactory<Void> callableFactory = new CallableFactory<Void>() {
        @Override
        public Callable<Void> newCallable(int callableId) {
            return new Callable<Void>() {

                @Override
                public Void call() throws Exception {
                    while (!partitionIdQueue.isEmpty()) {
                        Integer partitionId = partitionIdQueue.poll();
                        if (partitionId == null) {
                            break;
                        }
                        Path path = getSavedCheckpoint(superstep,
                                "_" + partitionId + CheckpointingUtils.CHECKPOINT_VERTICES_POSTFIX);

                        FSDataInputStream compressedStream = getFs().open(path);

                        DataInputStream stream = codec == null ? compressedStream
                                : new DataInputStream(codec.createInputStream(compressedStream));

                        Partition<I, V, E> partition = getConfiguration().createPartition(partitionId,
                                getContext());

                        partition.readFields(stream);

                        getPartitionStore().addPartition(partition);

                        stream.close();
                    }
                    return null;
                }

            };
        }
    };

    ProgressableUtils.getResultsWithNCallables(callableFactory, numThreads, "load-vertices-%d", getContext());

    LOG.info("Loaded checkpoint in " + (System.currentTimeMillis() - t0) + " ms, using " + numThreads
            + " threads");
}

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