InvisibleProgrammer commented on code in PR #5174:
URL: https://github.com/apache/hive/pull/5174#discussion_r1547456451
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ql/src/java/org/apache/hadoop/hive/ql/exec/tez/HiveSplitGenerator.java:
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@@ -154,6 +165,90 @@ private void prepare(InputInitializerContext
initializerContext) throws IOExcept
LOG.info("SplitLocationProvider: " + splitLocationProvider);
}
+ /**
+ * SplitSerializer is a helper class for taking care of serializing splits
to the tez scratch dir
+ * when a size criteria defined by
"hive.tez.split.fs.serialization.threshold" is met.
+ * It utilizes an ExecutorService for parallel writes to prevent a single
split write operation
+ * becoming the bottleneck (as write() is called from a loop currently).
+ */
+ class SplitSerializer {
+ // fields needed for filepath
+ private String queryId;
+ private String inputName;
+ private int vertexId;
+ private Path appStagingPath;
+ // metrics
+ private AtomicInteger timeSpentWithSplitWriteMs = new AtomicInteger(0);
+ private AtomicInteger splitsWritten = new AtomicInteger(0);
+ // lazy initialized filesystem and executor
+ private FileSystem fs;
+ private ExecutorService executor;
+
+ /**
+ * Lazy init filesystem and executor service: don't initialize if there is
no split serialized at all.
+ * No need to synchronize, this is called from a loop.
+ */
+ private void lazyInit() throws IOException {
+ if (fs != null) {
+ return;
+ }
+ queryId = jobConf.get(HiveConf.ConfVars.HIVEQUERYID.varname);
+ inputName = getContext().getInputName();
+ vertexId = getContext().getVertexId();
+ appStagingPath = TezCommonUtils.getTezSystemStagingPath(conf,
getContext().getApplicationId().toString());
+
+ fs = appStagingPath.getFileSystem(jobConf);
+ executor = Executors.newFixedThreadPool(8,
+ new ThreadFactoryBuilder().setDaemon(true)
+ .setNameFormat("HiveSplitGenerator.SplitSerializer Thread - " +
"#%d").build());
+ }
+
+ private InputDataInformationEvent write(int count, MRSplitProto mrSplit)
throws IOException {
+ lazyInit();
+
+ InputDataInformationEvent diEvent;
+ Path filePath = getSerializedFilePath(count);
+
+ // parallel writes for better performance (this is called from a loop)
+ executor.submit(() -> {
+ try {
+ long now = Time.monotonicNow();
+ try (FSDataOutputStream out = fs.create(filePath, false)) {
+ mrSplit.writeTo(out);
+ out.close();
+ }
+ splitsWritten.getAndIncrement();
+ long elapsed = Time.monotonicNow() - now;
+ timeSpentWithSplitWriteMs.getAndAdd((int) elapsed);
+ LOG.debug("Split #{} event to output path: {} written in {} ms",
count, filePath, elapsed);
+ } catch (IOException e) {
+ throw new RuntimeException(e);
+ }
+ });
+ // return the event now, we'll wait for the actual file write in close()
if needed
+ return InputDataInformationEvent.createWithSerializedPath(count,
filePath.toString());
+ }
+
+ private Path getSerializedFilePath(int index) {
+ // e.g. staging_dir/events/queryid/inputtable_InputDataInformationEvent_0
+ return new
Path(String.format("%s/events/%s/%d_%s_InputDataInformationEvent_%d",
appStagingPath, queryId,
+ vertexId, inputName, index));
+ }
+
+ private void close() throws IOException {
+ if (fs != null) {
+ executor.shutdown();
+ try {
+ executor.awaitTermination(5, TimeUnit.MINUTES);
Review Comment:
Is that a common practise that we have a hard-coded timeout? Do we have any
config about that?
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