[COMPRESS-291] decompress .7z archive very very slow

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.9
• Fix Version/s: 1.11
• Component/s: Compressors

Environment

Windows 7 x64, jdk1.7.0_21 x64

• Assignee: Unassigned
• Reporter: Robert Jansen
• Created: 22/Oct/14 21:52
• Updated: 16/Jul/16 11:32
• Resolved: 15/Mar/16 20:31

Description

I have 7z archives with one large image and many small files. The following code decompresses to a directory and returns the largest file. It is glacially slow and not usable for GB size files:

public File unSevenZipToDir(File sevenZipFile, File outputDir) {

File imgFile = null;
// Make sure output dir exists
outputDir.mkdirs();
if (outputDir.exists()) {

//FileInputStream stream;
try {

FileOutputStream output = null;
SevenZFile f7z = new SevenZFile(sevenZipFile);
SevenZArchiveEntry entry;
long maxSize = 0;

while ((entry = f7z.getNextEntry()) != null) {
if (entry != null) {
String s = entry.getName();

if (s != null) {
long sz = entry.getSize();

if (sz > 0) {
int count;
byte data[] = new byte[4096];

String outFileName = outputDir.getPath() + "/"
+ new File(entry.getName()).getName();

File outFile = new File(outFileName);

// Extract only if it does not already exist
if (outFile.exists() == false) {
System.out.println("Extracting " + s + " => size = " + sz);

FileOutputStream fos = new FileOutputStream(
outFile);

BufferedOutputStream dest = new BufferedOutputStream(
fos);

while ((count = f7z.read(data)) != -1)

{ dest.write(data, 0, count); }

dest.flush();
dest.close();

} else

{ System.out.println("Using already Extracted " + s + " => size = " + sz); }

if (s.endsWith(".h5") || s.endsWith(".tif") ||
s.endsWith(".cos") || s.endsWith(".nitf")

s.endsWith(".ntf")
s.endsWith(".jpg") && sz > maxSize) { maxSize = sz; imgFile = new File(outFileName); } } // end sz > 0 } // end s != null

} // end if entry
} // end while
f7z.close();

} catch (FileNotFoundException e)

{ // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); }

}
return imgFile;
}

Issue Links

• depends upon: COMPRESS-333 bz2 stream decompressor is 10x slower than it could be
• depends upon: COMPRESS-320 File listing and random access of 7Z files