From 4deae815b41e9dd02eb49bae3148f774c346e8a5 Mon Sep 17 00:00:00 2001
Date: Mon, 25 Jan 2021 15:48:35 +0800
Subject: 8254078: DataOutputStream is very slow post-disabling
 of Biased Locking

Summary: <JDK> : DataOutputStream is very slow post-disabling of Biased Locking
LLT: jtreg
Patch Type: backport
Bug url: https://bugs.openjdk.java.net/browse/JDK-8254078
---
 .../classes/java/io/DataInputStream.java      |  7 +++---
 .../classes/java/io/DataOutputStream.java     | 24 ++++++++++++-------
 2 files changed, 20 insertions(+), 11 deletions(-)

diff --git a/jdk/src/share/classes/java/io/DataInputStream.java b/jdk/src/share/classes/java/io/DataInputStream.java
index 7b24b74de..9516d0a7d 100644
--- a/jdk/src/share/classes/java/io/DataInputStream.java
+++ b/jdk/src/share/classes/java/io/DataInputStream.java
@@ -31,9 +31,10 @@ package java.io;
  * way. An application uses a data output stream to write data that
  * can later be read by a data input stream.
  * <p>
- * DataInputStream is not necessarily safe for multithreaded access.
- * Thread safety is optional and is the responsibility of users of
- * methods in this class.
+ * A DataInputStream is not safe for use by multiple concurrent
+ * threads. If a DataInputStream is to be used by more than one
+ * thread then access to the data input stream should be controlled
+ * by appropriate synchronization.
  *
  * @author  Arthur van Hoff
  * @see     java.io.DataOutputStream
diff --git a/jdk/src/share/classes/java/io/DataOutputStream.java b/jdk/src/share/classes/java/io/DataOutputStream.java
index 99fafed84..7628fb916 100644
--- a/jdk/src/share/classes/java/io/DataOutputStream.java
+++ b/jdk/src/share/classes/java/io/DataOutputStream.java
@@ -29,6 +29,11 @@ package java.io;
  * A data output stream lets an application write primitive Java data
  * types to an output stream in a portable way. An application can
  * then use a data input stream to read the data back in.
+ * <p>
+ * A DataOutputStream is not safe for use by multiple concurrent
+ * threads. If a DataOutputStream is to be used by more than one
+ * thread then access to the data output stream should be controlled
+ * by appropriate synchronization.
  *
  * @author  unascribed
  * @see     java.io.DataInputStream
@@ -164,8 +169,9 @@ class DataOutputStream extends FilterOutputStream implements DataOutput {
      * @see        java.io.FilterOutputStream#out
      */
     public final void writeShort(int v) throws IOException {
-        out.write((v >>> 8) & 0xFF);
-        out.write((v >>> 0) & 0xFF);
+        writeBuffer[0] = (byte)(v >>> 8);
+        writeBuffer[1] = (byte)(v >>> 0);
+        out.write(writeBuffer, 0, 2);
         incCount(2);
     }
 
@@ -179,8 +185,9 @@ class DataOutputStream extends FilterOutputStream implements DataOutput {
      * @see        java.io.FilterOutputStream#out
      */
     public final void writeChar(int v) throws IOException {
-        out.write((v >>> 8) & 0xFF);
-        out.write((v >>> 0) & 0xFF);
+        writeBuffer[0] = (byte)(v >>> 8);
+        writeBuffer[1] = (byte)(v >>> 0);
+        out.write(writeBuffer, 0, 2);
         incCount(2);
     }
 
@@ -194,10 +201,11 @@ class DataOutputStream extends FilterOutputStream implements DataOutput {
      * @see        java.io.FilterOutputStream#out
      */
     public final void writeInt(int v) throws IOException {
-        out.write((v >>> 24) & 0xFF);
-        out.write((v >>> 16) & 0xFF);
-        out.write((v >>>  8) & 0xFF);
-        out.write((v >>>  0) & 0xFF);
+        writeBuffer[0] = (byte)(v >>> 24);
+        writeBuffer[1] = (byte)(v >>> 16);
+        writeBuffer[2] = (byte)(v >>> 8);
+        writeBuffer[3] = (byte)(v >>> 0);
+        out.write(writeBuffer, 0, 4);
         incCount(4);
     }
 
-- 
2.19.0