Package org.apache.commons.io.input

Class MemoryMappedFileInputStream

java.lang.Object
java.io.InputStream
org.apache.commons.io.input.AbstractInputStream
org.apache.commons.io.input.MemoryMappedFileInputStream
All Implemented Interfaces:
Closeable, AutoCloseable
public final class MemoryMappedFileInputStream extends AbstractInputStream
An InputStream that utilizes memory mapped files to improve performance. A sliding window of the file is mapped to memory to avoid mapping the entire file to memory at one time. The size of the sliding buffer is configurable.

For most operating systems, mapping a file into memory is more expensive than reading or writing a few tens of kilobytes of data. From the standpoint of performance. it is generally only worth mapping relatively large files into memory.

Note: Use of this class does not necessarily obviate the need to use a BufferedInputStream. Depending on the use case, the use of buffering may still further improve performance. For example:

To build an instance, use MemoryMappedFileInputStream.Builder. 


 BufferedInputStream s = new BufferedInputStream(new GzipInputStream(
   MemoryMappedFileInputStream.builder()
     .setPath(path)
     .setBufferSize(256 * 1024)
     .get()));

should outperform: 

 new GzipInputStream(new MemoryMappedFileInputStream(path))
 

 GzipInputStream s = new GzipInputStream(
   MemoryMappedFileInputStream.builder()
     .setPath(path)
     .setBufferSize(256 * 1024)
     .get());
Since:
2.12.0
See Also: