Java 在合并多个ByteBuff时，在非OLEDBYTEBuffAllocator和在netty中池中进行选择

我使用图书馆下载文件。 例如，我需要从一台主机下载500个文件，每个文件大小约为10MB，然后将这些文件写入磁盘。对于本例，我将提供以下代码：

声明异步HttpClient。我使用ResponseBodyPartFactory.LAZY来避免复制到java堆中

final AsyncHttpClient asyncHttpClient = Dsl.asyncHttpClient(Dsl.config()
             .setFollowRedirect(true)
             .setResponseBodyPartFactory(AsyncHttpClientConfig.ResponseBodyPartFactory.LAZY)
             .setUseOpenSsl(true)
             .setRequestTimeout(6000000)
             .setUseNativeTransport(true)
             .build());

声明ExecutorService，它将用于写入文件。使用固定大小，因为默认执行器服务可以创建1000多个线程（他使用cachedThreadPool）

文件下载代码。我使用localhost是因为我想获得最大的下载速度，然后将这些文件写回磁盘。主要部分在方法onBodyPartReceived

 for (int i = 0; i < downloadCount; i++) {
 asyncHttpClient.prepareGet("http://localhost/Pizigani_1367_Chart_10MB.jpg").execute(new AsyncHandler<Void>() {
     private long currentFilePosition;
     private AsynchronousFileChannel fileChannel;
     private CompositeByteBuf compositeByteBuf;


     @Override
     public AsyncHandler.State onStatusReceived(HttpResponseStatus status) throws IOException {
         if (status.getStatusCode() != 200) {
             return State.ABORT;
         }
         this.fileChannel = AsynchronousFileChannel.open(Paths.get("/tmp/" + UUID.randomUUID().toString() + "file.jpg"), EnumSet.of(StandardOpenOption.WRITE, StandardOpenOption.TRUNCATE_EXISTING, StandardOpenOption.CREATE), executorService);
         this.compositeByteBuf = Unpooled.compositeBuffer(16);
         return State.CONTINUE;
     }

     @Override
     public State onHeadersReceived(HttpHeaders headers) {
         return State.CONTINUE;
     }

     @Override
     public void onThrowable(Throwable t) {
     }

     @Override
     public Void onCompleted() {
         return null;
     }

     @Override
     public State onBodyPartReceived(HttpResponseBodyPart content) {
         final ByteBuf responseByteBuf = ((LazyResponseBodyPart) content).getBuf().retain();
         final CompositeByteBuf compositeByteBuf = this.compositeByteBuf.addComponent(true, responseByteBuf);
         if (compositeByteBuf.numComponents() == compositeByteBuf.maxNumComponents() || content.isLast()) {
             final ByteBuf mergedDirectBuffer = UnpooledByteBufAllocator.DEFAULT.directBuffer(compositeByteBuf.readableBytes()); //or Pooled?
             for (ByteBuffer b : compositeByteBuf.nioBuffers()) {
                 mergedDirectBuffer.writeBytes(b);
             }
             compositeByteBuf.release();
             ByteBuffer asyncBuffer = mergedDirectBuffer.nioBuffer().rewind();

             long currentFilePosition= this.currentFilePosition;
             this.currentFilePosition += mergedDirectBuffer.readableBytes();
             this.compositeByteBuf = Unpooled.compositeBuffer(16);
             fileChannel.write(asyncBuffer, currentFilePosition, mergedDirectBuffer, new CompletionHandler<>() {
                 @Override
                 public void completed(Integer result, ByteBuf attachment) {
                     attachment.release();
                     if (content.isLast()) {
                         try {
                             fileChannel.close();
                         } catch (IOException e) {
                             throw new UncheckedIOException(e);
                         }
                     }
                 }

                 @Override
                 public void failed(Throwable exc, ByteBuf attachment) {
                     attachment.release();
                     try {
                         fileChannel.close();
                     } catch (IOException e) {
                         throw new UncheckedIOException(e);
                     }
                 }
             });

         }

         return State.CONTINUE;
     }
 });

所以我提出了一个问题。 在将缓冲区合并到新的直接缓冲区时，我应该选择池式还是非池式？只是我的一些测量结果表明，未经冷却的速度更快，而共用的通常不会释放内存

将组合缓冲区写入磁盘的方法正确吗？也许有更好的方法？ 我不太了解内蒂

 for (int i = 0; i < downloadCount; i++) {
 asyncHttpClient.prepareGet("http://localhost/Pizigani_1367_Chart_10MB.jpg").execute(new AsyncHandler<Void>() {
     private long currentFilePosition;
     private AsynchronousFileChannel fileChannel;
     private CompositeByteBuf compositeByteBuf;


     @Override
     public AsyncHandler.State onStatusReceived(HttpResponseStatus status) throws IOException {
         if (status.getStatusCode() != 200) {
             return State.ABORT;
         }
         this.fileChannel = AsynchronousFileChannel.open(Paths.get("/tmp/" + UUID.randomUUID().toString() + "file.jpg"), EnumSet.of(StandardOpenOption.WRITE, StandardOpenOption.TRUNCATE_EXISTING, StandardOpenOption.CREATE), executorService);
         this.compositeByteBuf = Unpooled.compositeBuffer(16);
         return State.CONTINUE;
     }

     @Override
     public State onHeadersReceived(HttpHeaders headers) {
         return State.CONTINUE;
     }

     @Override
     public void onThrowable(Throwable t) {
     }

     @Override
     public Void onCompleted() {
         return null;
     }

     @Override
     public State onBodyPartReceived(HttpResponseBodyPart content) {
         final ByteBuf responseByteBuf = ((LazyResponseBodyPart) content).getBuf().retain();
         final CompositeByteBuf compositeByteBuf = this.compositeByteBuf.addComponent(true, responseByteBuf);
         if (compositeByteBuf.numComponents() == compositeByteBuf.maxNumComponents() || content.isLast()) {
             final ByteBuf mergedDirectBuffer = UnpooledByteBufAllocator.DEFAULT.directBuffer(compositeByteBuf.readableBytes()); //or Pooled?
             for (ByteBuffer b : compositeByteBuf.nioBuffers()) {
                 mergedDirectBuffer.writeBytes(b);
             }
             compositeByteBuf.release();
             ByteBuffer asyncBuffer = mergedDirectBuffer.nioBuffer().rewind();

             long currentFilePosition= this.currentFilePosition;
             this.currentFilePosition += mergedDirectBuffer.readableBytes();
             this.compositeByteBuf = Unpooled.compositeBuffer(16);
             fileChannel.write(asyncBuffer, currentFilePosition, mergedDirectBuffer, new CompletionHandler<>() {
                 @Override
                 public void completed(Integer result, ByteBuf attachment) {
                     attachment.release();
                     if (content.isLast()) {
                         try {
                             fileChannel.close();
                         } catch (IOException e) {
                             throw new UncheckedIOException(e);
                         }
                     }
                 }

                 @Override
                 public void failed(Throwable exc, ByteBuf attachment) {
                     attachment.release();
                     try {
                         fileChannel.close();
                     } catch (IOException e) {
                         throw new UncheckedIOException(e);
                     }
                 }
             });

         }

         return State.CONTINUE;
     }
 });

        if (compositeByteBuf.numComponents() == compositeByteBuf.maxNumComponents() || content.isLast()) {
            final ByteBuf mergedDirectBuffer = UnpooledByteBufAllocator.DEFAULT.directBuffer(compositeByteBuf.readableBytes()); //or Pooled?
            for (ByteBuffer b : compositeByteBuf.nioBuffers()) {
                mergedDirectBuffer.writeBytes(b);
            }
            compositeByteBuf.release();
            ByteBuffer asyncBuffer = mergedDirectBuffer.nioBuffer().rewind();

            long currentFilePosition= this.currentFilePosition;
            this.currentFilePosition += mergedDirectBuffer.readableBytes();
            this.compositeByteBuf = Unpooled.compositeBuffer(16);
            fileChannel.write(asyncBuffer, currentFilePosition, mergedDirectBuffer, new CompletionHandler<>() {