private void readOnDiskMapOutput(
Configuration conf, FileSystem fs, Path path, List<String> keys, List<String> values)
throws IOException {
FSDataInputStream in = CryptoUtils.wrapIfNecessary(conf, fs.open(path));
IFile.Reader<Text, Text> reader =
new IFile.Reader<Text, Text>(conf, in, fs.getFileStatus(path).getLen(), null, null);
DataInputBuffer keyBuff = new DataInputBuffer();
DataInputBuffer valueBuff = new DataInputBuffer();
Text key = new Text();
Text value = new Text();
while (reader.nextRawKey(keyBuff)) {
key.readFields(keyBuff);
keys.add(key.toString());
reader.nextRawValue(valueBuff);
value.readFields(valueBuff);
values.add(value.toString());
}
}
private TaskAttemptID[] copyMapOutput(
MapHost host, DataInputStream input, Set<TaskAttemptID> remaining) {
MapOutput<K, V> mapOutput = null;
TaskAttemptID mapId = null;
long decompressedLength = -1;
long compressedLength = -1;
try {
long startTime = System.currentTimeMillis();
int forReduce = -1;
// Read the shuffle header
try {
ShuffleHeader header = new ShuffleHeader();
header.readFields(input);
mapId = TaskAttemptID.forName(header.mapId);
compressedLength = header.compressedLength;
decompressedLength = header.uncompressedLength;
forReduce = header.forReduce;
} catch (IllegalArgumentException e) {
badIdErrs.increment(1);
LOG.warn("Invalid map id ", e);
// Don't know which one was bad, so consider all of them as bad
return remaining.toArray(new TaskAttemptID[remaining.size()]);
}
InputStream is = input;
is = CryptoUtils.wrapIfNecessary(jobConf, is, compressedLength);
compressedLength -= CryptoUtils.cryptoPadding(jobConf);
decompressedLength -= CryptoUtils.cryptoPadding(jobConf);
// Do some basic sanity verification
if (!verifySanity(compressedLength, decompressedLength, forReduce, remaining, mapId)) {
return new TaskAttemptID[] {mapId};
}
if (LOG.isDebugEnabled()) {
LOG.debug(
"header: "
+ mapId
+ ", len: "
+ compressedLength
+ ", decomp len: "
+ decompressedLength);
}
// Get the location for the map output - either in-memory or on-disk
try {
mapOutput = merger.reserve(mapId, decompressedLength, id);
} catch (IOException ioe) {
// kill this reduce attempt
ioErrs.increment(1);
scheduler.reportLocalError(ioe);
return EMPTY_ATTEMPT_ID_ARRAY;
}
// Check if we can shuffle *now* ...
if (mapOutput == null) {
LOG.info("fetcher#" + id + " - MergeManager returned status WAIT ...");
// Not an error but wait to process data.
return EMPTY_ATTEMPT_ID_ARRAY;
}
// The codec for lz0,lz4,snappy,bz2,etc. throw java.lang.InternalError
// on decompression failures. Catching and re-throwing as IOException
// to allow fetch failure logic to be processed
try {
// Go!
LOG.info(
"fetcher#"
+ id
+ " about to shuffle output of map "
+ mapOutput.getMapId()
+ " decomp: "
+ decompressedLength
+ " len: "
+ compressedLength
+ " to "
+ mapOutput.getDescription());
mapOutput.shuffle(host, is, compressedLength, decompressedLength, metrics, reporter);
} catch (java.lang.InternalError e) {
LOG.warn("Failed to shuffle for fetcher#" + id, e);
throw new IOException(e);
}
// Inform the shuffle scheduler
long endTime = System.currentTimeMillis();
scheduler.copySucceeded(mapId, host, compressedLength, endTime - startTime, mapOutput);
// Note successful shuffle
remaining.remove(mapId);
metrics.successFetch();
return null;
} catch (IOException ioe) {
ioErrs.increment(1);
if (mapId == null || mapOutput == null) {
LOG.info(
"fetcher#"
+ id
+ " failed to read map header"
+ mapId
+ " decomp: "
+ decompressedLength
+ ", "
+ compressedLength,
ioe);
if (mapId == null) {
return remaining.toArray(new TaskAttemptID[remaining.size()]);
} else {
return new TaskAttemptID[] {mapId};
}
}
LOG.warn("Failed to shuffle output of " + mapId + " from " + host.getHostName(), ioe);
// Inform the shuffle-scheduler
mapOutput.abort();
metrics.failedFetch();
return new TaskAttemptID[] {mapId};
}
}