Buffered Stream in Java: What Happens When You Buffer It Again?
In case the answer is negative, may I know the reason behind it? Please note that although I am referring to input streams, the same query applies to output streams as well. One possible solution is to use Buffered-Streams, as they are distinct from regular streams. According to this article on Oracle’s website (http://www.oracle.com/technetwork/articles/javase/perftuning-137844.html), this approach can accelerate the IO-process by minimizing the number of read() operations performed in the background.
What is the result of buffering a buffered stream in java?
Was writing the javadoc for :
/** * . Buffers the input stream so do not pass in a BufferedInputStream . */ public static void meth(InputStream is) throws IOException < BufferedInputStream bis = new BufferedInputStream(is, INPUT_STREAM_BUFFER_SIZE); // rest omitted >Is it an issue to pass a buffered input stream as an input? Therefore, the following:
InputStream is = new BufferedInputStream(new FileInputStream("C:/file"), SIZE); meth(is); Is it preferable to buffer is into bis or simply use the already buffered and set is with bis = is ? Additionally, would using varying buffer sizes have an impact? If this applies to input streams , it may also be applicable to output stream s.
Is there any issue with submitting a buffered input stream into the system?
Although there may be a slight additional cost in implementing this, it is insignificant when compared to the total expense of input reading.
By examining the BufferedInputStream code, specifically the read1 function, you can observe that it has been optimized for efficient block reads when buffered streams are stacked.
In regards to the sample code, would Java be able to recognize that it is already buffered and then apply the appropriate settings?
Typically, Java (the language and compiler) lacks comprehension of the meaning behind Java library classes. In this instance, the implementation of such an optimization would have minimal advantages, rendering it not worth pursuing.
You have the option to explicitly write your method for performing this task using meth . However, in my opinion, it is unlikely to have a significant impact.
I am unsure why in read1, they only copy to the input buffer if the requested length is less than the buffer’s length or if there is a marked position in the input stream.
Based on your reference to it, I understand that you are talking about the code present in read1 .
if (len >= getBufIfOpen().length && markpos
The initial statement implies that if the user requests data less than the buffer size, buffering should not be short-circuit as executing a read(byte[], int, int) operation with a small requested length would be suboptimal.
The second component pertains to the implementation of mark/reset. Rather than utilizing mark/reset on the underlying stream (which may not be supported), a BufferedInputStream employs the buffer to execute it. The logic you are witnessing is a part of that implementation. For further details, you can refer to the comments in the source code and understand it yourself.
If you choose to buffer the stream on two occasions, it will operate, albeit at a slower pace and with a higher consumption of memory, compared to buffering it only once.
It is essential to record that your stream has buffering capabilities to inform users that there is no need for them to buffer it themselves.
It’s preferable to dissuade rather than forcefully obstruct such misuse.
Java’s detection does not include double buffering.
The responsibility of preventing this issue lies with the user, as the BufferedInputStream cannot determine if the InputStream provided in the constructor is buffered or not.
Below is the constructor code for BufferedInputStream .
public BufferedInputStream(InputStream in, int size) < super(in); if (size buf = new byte[size]; > Are there any issues with implementing double buffering on a stream?
In brief, the response is affirmative.
The concept of buffering involves boosting velocity by storing data in memory and writing it out in chunks, often to slow IO. Double buffering entails storing data in memory, then transferring it to another location in memory, which comes at a cost to speed.
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Java IO — Buffered Streams (BufferedInputStream
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Using buffered streams for sending objects?
At present, I am utilizing Java sockets for output streams and client-server application for input streams. It’s not being employed for bufferedoutputstream in either case.
The serialized objects (writeObject() method) are exchanged between the client and server.
Would it be logical to incorporate BufferedOutputStream and bufferedinputstream for improved speed in this scenario?
Should I include a flush() statement or is it unnecessary when performing a flush?
In this scenario, would it be logical to utilize BufferedOutputStream and BufferedInputStream for improved speed?
It’s highly unlikely that the first point makes any sense.
The implementation of the object stream involves the use of a private class named BlockDataOutputStream that provides buffering capabilities. Adding another level of buffering by manually wrapping the stream is not recommended as it can potentially decrease performance.
Should I include a flush() statement or is it unnecessary to flush?
Although flushing may be required, the appropriate timing is not universally determined.
- On the one hand, if you flush too often, you generate extra network traffic.
- On the other hand, if you don’t flush when it is needed, the server can stall waiting for an object that the client has written but not flushed.
The balance between the two syndromes must be determined based on the interaction patterns between the client and server in your application. This includes considering whether the messaging patterns are synchronous, such as message/response, or asynchronous, such as message streaming.
To ensure accuracy, forensic testing is required to measure system performance and identify syscalls and network packet sending timings. To provide a comprehensive response, this testing would need to be repeated for multiple scenarios. Additionally, I suggest reviewing the Java library code personally to corroborate my initial analysis.
A well-designed benchmark would be capable of detecting a slight performance disparity, although it is likely to be only marginally worse.
Upon completion of my previous writing, I stumbled upon a Q&A — Performance issue — that recommends utilizing Javas Object streams with Sockets by implementing either BufferedInputStream or BufferedOutputStream to potentially yield performance enhancements. However, it remains unclear whether the reported performance improvement is genuine and not a result of a warmup artefact. Additionally, it is uncertain whether the improvement is solely due to the addition of the flush() call, as the flush could prompt the network stack to promptly transmit the data.
I think these links might help you:
The flush method ensures that any buffered output bytes are written out by flushing the output stream. By calling flush, it is implied that any bytes that were previously written and buffered by the output stream’s implementation should be immediately written to their intended destination.
What distinguishes java.io.Buffer* streams from standard streams?
To enhance performance, the underlying input stream doesn’t read bytes one by one. Instead, it reads enough bytes to fill a buffer array, minimizing the number of reads on the input stream.
Check out this link on Oracle’s website regarding performance tuning tips for Java SE: http://www.oracle.com/technetwork/articles/javase/perftuning-137844.html
To initiate the conversation, here are some fundamental guidelines for enhancing I/O speed: refrain from accessing the disk, underlying operating system, making method calls, and processing individual bytes or characters.
Buffered-Streams are known to improve IO processes by reducing the number of read() operations performed in the background.
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Buffered and Unbuffered Streams in Java
While reading the Java IO documentation, I wanted to confirm if my understanding was correct.
Input streams that are unbuffered include FileInputStream, also known as msdt_a1.
Output streams that are unbuffered include FileOutputStream, OutputStreamWriter, and FileWriter.
Output streams that are buffered. — PrintStream, PrintWriter
Furthermore, the unbuffered streams can be transformed into buffered versions through the use of BufferedInputStream, BufferedOutputStream, BufferedReader, and BufferedWriter streams.
Upon examination, I noticed that the internal byte-buffer for bytes in Character Streams, including InputStreamReader, FileReader, OutputStreamWriter, and FileWriter, is managed before they are transmitted through the stream. This byte-buffer is not within our jurisdiction. As a result, buffering in Character Streams pertains to the high-level character buffer utilized for storing characters coming that enters and exits the program.
Is everything I said correct?
I acknowledge that the problem with buffering can vary based on how it is implemented, but I would like to verify the accuracy of the information found in the javadocs.
- Any InputStream / Reader that reads directly from an external source (FileInputStream, SocketInputStream, etc.) is ‘raw’ and considered unbuffered. (Though in reality, there is probably some buffering going on, depends on the implementation)
- Any ‘raw’ InputStream or Reader can be buffered by a BufferedInputStream or BufferedReader.
- Same assumptions for OuputStreams / Writers.
- Other stream decorators (i.e. GZIPInputStream, MD5InputStream, YourSpecialObjectWriter) probably do some buffering, but its not very harmful to buffer the source.
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Buffered Streams
Most of the examples we’ve seen so far use unbuffered I/O. This means each read or write request is handled directly by the underlying OS. This can make a program much less efficient, since each such request often triggers disk access, network activity, or some other operation that is relatively expensive.
To reduce this kind of overhead, the Java platform implements buffered I/O streams. Buffered input streams read data from a memory area known as a buffer; the native input API is called only when the buffer is empty. Similarly, buffered output streams write data to a buffer, and the native output API is called only when the buffer is full.
A program can convert an unbuffered stream into a buffered stream using the wrapping idiom we’ve used several times now, where the unbuffered stream object is passed to the constructor for a buffered stream class. Here’s how you might modify the constructor invocations in the CopyCharacters example to use buffered I/O:
inputStream = new BufferedReader(new FileReader("xanadu.txt")); outputStream = new BufferedWriter(new FileWriter("characteroutput.txt")); There are four buffered stream classes used to wrap unbuffered streams: BufferedInputStream and BufferedOutputStream create buffered byte streams, while BufferedReader and BufferedWriter create buffered character streams.
Flushing Buffered Streams
It often makes sense to write out a buffer at critical points, without waiting for it to fill. This is known as flushing the buffer.
Some buffered output classes support autoflush, specified by an optional constructor argument. When autoflush is enabled, certain key events cause the buffer to be flushed. For example, an autoflush PrintWriter object flushes the buffer on every invocation of println or format . See Formatting for more on these methods.
To flush a stream manually, invoke its flush method. The flush method is valid on any output stream, but has no effect unless the stream is buffered.