[
https://issues.apache.org/jira/browse/BEAM-5439?focusedWorklogId=158357&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-158357
]
ASF GitHub Bot logged work on BEAM-5439:
----------------------------------------
Author: ASF GitHub Bot
Created on: 24/Oct/18 22:30
Start Date: 24/Oct/18 22:30
Worklog Time Spent: 10m
Work Description: lukecwik closed pull request #6812: [BEAM-5439] fixes
performance issue in StringUtf8Coder
URL: https://github.com/apache/beam/pull/6812
This is a PR merged from a forked repository.
As GitHub hides the original diff on merge, it is displayed below for
the sake of provenance:
As this is a foreign pull request (from a fork), the diff is supplied
below (as it won't show otherwise due to GitHub magic):
diff --git
a/sdks/java/core/src/main/java/org/apache/beam/sdk/coders/StringUtf8Coder.java
b/sdks/java/core/src/main/java/org/apache/beam/sdk/coders/StringUtf8Coder.java
index 339b8f13cf1..57107813e7d 100644
---
a/sdks/java/core/src/main/java/org/apache/beam/sdk/coders/StringUtf8Coder.java
+++
b/sdks/java/core/src/main/java/org/apache/beam/sdk/coders/StringUtf8Coder.java
@@ -18,8 +18,7 @@
package org.apache.beam.sdk.coders;
import com.google.common.base.Utf8;
-import java.io.DataInputStream;
-import java.io.DataOutputStream;
+import com.google.common.io.ByteStreams;
import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
@@ -46,19 +45,19 @@ public static StringUtf8Coder of() {
private static final StringUtf8Coder INSTANCE = new StringUtf8Coder();
private static final TypeDescriptor<String> TYPE_DESCRIPTOR = new
TypeDescriptor<String>() {};
- private static void writeString(String value, DataOutputStream dos) throws
IOException {
+ private static void writeString(String value, OutputStream dos) throws
IOException {
byte[] bytes = value.getBytes(StandardCharsets.UTF_8);
VarInt.encode(bytes.length, dos);
dos.write(bytes);
}
- private static String readString(DataInputStream dis) throws IOException {
+ private static String readString(InputStream dis) throws IOException {
int len = VarInt.decodeInt(dis);
if (len < 0) {
throw new CoderException("Invalid encoded string length: " + len);
}
byte[] bytes = new byte[len];
- dis.readFully(bytes);
+ ByteStreams.readFully(dis, bytes);
return new String(bytes, StandardCharsets.UTF_8);
}
@@ -82,7 +81,7 @@ public void encode(String value, OutputStream outStream,
Context context) throws
outStream.write(bytes);
}
} else {
- writeString(value, new DataOutputStream(outStream));
+ writeString(value, outStream);
}
}
@@ -98,7 +97,7 @@ public String decode(InputStream inStream, Context context)
throws IOException {
return new String(bytes, StandardCharsets.UTF_8);
} else {
try {
- return readString(new DataInputStream(inStream));
+ return readString(inStream);
} catch (EOFException | UTFDataFormatException exn) {
// These exceptions correspond to decoding problems, so change
// what kind of exception they're branded as.
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Issue Time Tracking
-------------------
Worklog Id: (was: 158357)
Time Spent: 20m (was: 10m)
> StringUtf8Coder is slower than expected
> ---------------------------------------
>
> Key: BEAM-5439
> URL: https://issues.apache.org/jira/browse/BEAM-5439
> Project: Beam
> Issue Type: Bug
> Components: sdk-java-core
> Affects Versions: 2.6.0
> Reporter: Julien Tournay
> Assignee: Julien Tournay
> Priority: Major
> Labels: perfomance
> Time Spent: 20m
> Remaining Estimate: 0h
>
> While working on Scio's next version, I noticed that {{StringUtf8Coder}} is
> slower than expected.
> I wrote a small micro-benchmark using {{jmh}} that serialises a (scala) List
> of a 1000 Strings using a custom {{Coder[List[_]]}}. While profiling it, I
> noticed that a lot of time is spent in
> {{java.io.DataInputStream.<init>(java.io.InputStream)}}.
> Looking into the code for
> {{StringUtf8Coder}}, the {{readString}} method is directly reading bytes. It
> therefore does not seem that a {{DataInputStream}} is necessary.
> I replaced {{StringUtf8Coder}} with a {{Coder[String]}} implementation (in
> Scala), that is essentially the same as {{StringUtf8Coder}} but is not using
> {{DataInputStream}}.
>
> {code:scala}
> private final object ScioStringCoder extends AtomicCoder[String] {
> import org.apache.beam.sdk.util.VarInt
> import java.nio.charset.StandardCharsets
> import org.apache.beam.sdk.values.TypeDescriptor
> import com.google.common.base.Utf8
> def decode(dis: InputStream): String = {
> val len = VarInt.decodeInt(dis)
> if (len < 0) {
> throw new CoderException("Invalid encoded string length: " + len)
> }
> val bytes = new Array[Byte](len)
> dis.read(bytes)
> return new String(bytes, StandardCharsets.UTF_8)
> }
> def encode(value: String, outStream: OutputStream): Unit = {
> val bytes = value.getBytes(StandardCharsets.UTF_8)
> VarInt.encode(bytes.length, outStream)
> outStream.write(bytes)
> }
> override def verifyDeterministic() = ()
> override def consistentWithEquals() = true
> private val TYPE_DESCRIPTOR = new TypeDescriptor[String] {}
> override def getEncodedTypeDescriptor() = TYPE_DESCRIPTOR
> override def getEncodedElementByteSize(value: String) = {
> if (value == null) {
> throw new CoderException("cannot encode a null String")
> }
> val size = Utf8.encodedLength(value)
> VarInt.getLength(size) + size
> }
> }
> {code}
>
> Using that {{Coder}} is about 27% faster than {{StringUtf8Coder}}. I've added
> the jmh output in "Docs Text"
> Is there any particular reason to use {{DataInputStream}} ?
> Do you think we can remove that to make {{StringUtf8Coder}} more efficient ?
>
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