Using a PipedOutputStream to write a file - "Broken Pipe" happens when GZIPOutputStream is introduced
Tags: java, pipedoutputstream, brokenpipe, gzipoutputstream
Published: 2023-08-13 01:05:29

Have you ever encountered the dreaded "Broken Pipe" error when using a `PipedOutputStream` to write a file? If you have, then you're not alone. Many developers have faced this issue when trying to introduce a `GZIPOutputStream` into the mix. But fear not, for in this article, we will explore this problem and provide you with a solution.

First, let's understand what a `PipedOutputStream` does. It is a class in Java that is used to write data into a pipe. This pipe is connected to a `PipedInputStream`, allowing another thread to read the data from the pipe. It's a convenient way to pass data between threads.

Now, imagine that you have a scenario where you want to write a file and compress it using `GZIPOutputStream`. You might think it's as simple as connecting a `GZIPOutputStream` to the `PipedOutputStream` and start writing data. But that's where the problem arises.

When you introduce the `GZIPOutputStream`, it adds an extra layer of complexity. It compresses the data before writing it to the underlying stream. The issue is that the `PipedOutputStream` has a limited buffer size. If the buffer becomes full and the consumer thread is not reading the data fast enough, the `PipedOutputStream` will block the producer thread until there is space in the buffer. However, the `GZIPOutputStream` is not aware of this and assumes that it can write as much data as it wants.

So, what happens when the `GZIPOutputStream` tries to write data to a full buffer? It throws a `java.io.IOException` with the message "Broken Pipe." This error occurs because the pipe has been closed by the `PipedInputStream` due to the producer thread being blocked for too long.

Now that we understand the cause of the problem, let's look at a solution. One way to overcome this issue is to increase the buffer size of the `PipedOutputStream`. You can do this by creating your own subclass of `PipedOutputStream` and overriding the `connect` method to set a larger buffer size.

\`\`\`java public class MyPipedOutputStream extends PipedOutputStream { public MyPipedOutputStream(PipedInputStream snk, int bufferSize) throws IOException { super(snk); try { Field bufferField = PipedOutputStream.class.getDeclaredField("buffer"); bufferField.setAccessible(true); bufferField.set(this, new byte\[bufferSize\]); } catch (NoSuchFieldException | IllegalAccessException e) { throw new IOException("Failed to set buffer size", e); } } } \`\`\`

By using this custom `PipedOutputStream` with a larger buffer size, you can avoid the "Broken Pipe" error when using a `GZIPOutputStream`. Remember to use it in conjunction with a `PipedInputStream` and handle the data reading appropriately.

So, the next time you encounter the "Broken Pipe" error when using a `PipedOutputStream` with a `GZIPOutputStream`, don't panic. Instead, try using a custom `PipedOutputStream` with a larger buffer size, and your problem will be solved.

References:
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*   [PipedOutputStream - Java Documentation](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/io/PipedOutputStream.html)
*   [GZIPOutputStream - Java Documentation](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/zip/GZIPOutputStream.html)