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https://issues.apache.org/jira/browse/DRILL-5207?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15843722#comment-15843722
]
ASF GitHub Bot commented on DRILL-5207:
---------------------------------------
Github user parthchandra commented on a diff in the pull request:
https://github.com/apache/drill/pull/723#discussion_r98269034
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/store/parquet/columnreaders/AsyncPageReader.java
---
@@ -41,26 +42,33 @@
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.concurrent.Callable;
+import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
+import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.TimeUnit;
import static org.apache.parquet.column.Encoding.valueOf;
class AsyncPageReader extends PageReader {
static final org.slf4j.Logger logger =
org.slf4j.LoggerFactory.getLogger(AsyncPageReader.class);
-
private ExecutorService threadPool;
- private Future<ReadStatus> asyncPageRead;
+ private long queueSize;
+ private LinkedBlockingQueue<ReadStatus> pageQueue;
+ private ConcurrentLinkedQueue<Future<Boolean>> asyncPageRead;
+ private long totalPageValuesRead = 0;
AsyncPageReader(ColumnReader<?> parentStatus, FileSystem fs, Path path,
ColumnChunkMetaData columnChunkMetaData) throws
ExecutionSetupException {
super(parentStatus, fs, path, columnChunkMetaData);
- if (threadPool == null) {
+ if (threadPool == null & asyncPageRead == null) {
--- End diff --
Thanks for catching this!
> Improve Parquet scan pipelining
> -------------------------------
>
> Key: DRILL-5207
> URL: https://issues.apache.org/jira/browse/DRILL-5207
> Project: Apache Drill
> Issue Type: Bug
> Components: Storage - Parquet
> Affects Versions: 1.9.0
> Reporter: Parth Chandra
> Assignee: Parth Chandra
> Fix For: 1.10
>
>
> The parquet reader's async page reader is not quite efficiently pipelined.
> The default size of the disk read buffer is 4MB while the page reader reads
> ~1MB at a time. The Parquet decode is also processing 1MB at a time. This
> means the disk is idle while the data is being processed. Reducing the buffer
> to 1MB will reduce the time the processing thread waits for the disk read
> thread.
> Additionally, since the data to process a page may be more or less than 1MB,
> a queue of pages will help so that the disk scan does not block (until the
> queue is full), waiting for the processing thread.
> Additionally, the BufferedDirectBufInputStream class reads from disk as soon
> as it is initialized. Since this is called at setup time, this increases the
> setup time for the query and query execution does not begin until this is
> completed.
> There are a few other inefficiencies - options are read every time a page
> reader is created. Reading options can be expensive.
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