Reduce byte[] allocations by reusing buffers

Reduces byte[] allocations from 280MB to <4MB when reading a 133MB base64 stream. Messured with JFR.
apache · May 10, 2021 · 6bd8d86 · 6bd8d86
1 parent a7c5af9
commit 6bd8d86
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Showing 2 changed files with 9 additions and 2 deletions.
diff --git a/src/main/java/org/apache/commons/codec/binary/BaseNCodec.java b/src/main/java/org/apache/commons/codec/binary/BaseNCodec.java
@@ -75,6 +75,7 @@ static class Context {
          * Buffer for streaming.
          */
         byte[] buffer;
+        byte[] bufferCache;
 
         /**
          * Position where next character should be written in the buffer.
@@ -569,7 +570,11 @@ public String encodeToString(final byte[] pArray) {
      */
     protected byte[] ensureBufferSize(final int size, final Context context){
         if (context.buffer == null) {
-            context.buffer = new byte[Math.max(size, getDefaultBufferSize())];
+            int bufferSize = Math.max(size, getDefaultBufferSize());
+            if (context.bufferCache == null || context.bufferCache.length != bufferSize) {
+                context.bufferCache = new byte[bufferSize];
+            }
+            context.buffer = context.bufferCache;
             context.pos = 0;
             context.readPos = 0;
 

diff --git a/src/main/java/org/apache/commons/codec/binary/BaseNCodecInputStream.java b/src/main/java/org/apache/commons/codec/binary/BaseNCodecInputStream.java
@@ -39,12 +39,15 @@ public class BaseNCodecInputStream extends FilterInputStream {
 
     private final byte[] singleByte = new byte[1];
 
+    private final byte[] buf;
+
     private final Context context = new Context();
 
     protected BaseNCodecInputStream(final InputStream input, final BaseNCodec baseNCodec, final boolean doEncode) {
         super(input);
         this.doEncode = doEncode;
         this.baseNCodec = baseNCodec;
+        this.buf = new byte[doEncode ? 4096 : 8192];
     }
 
     /**
@@ -171,7 +174,6 @@ public int read(final byte array[], final int offset, final int len) throws IOEx
         */
         while (readLen == 0) {
             if (!baseNCodec.hasData(context)) {
-                final byte[] buf = new byte[doEncode ? 4096 : 8192];
                 final int c = in.read(buf);
                 if (doEncode) {
                     baseNCodec.encode(buf, 0, c, context);