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Does 7-Zip take advantage of multiprocessor or multi-core systems when compressing?

For example, would there be a close to 16 times speed-up on a 16 core system assuming no disk or memory bottlenecks?

Or is it is limited to 2 threads (2 times speed-up on systems with more than one CPU or core)?


Edit: To summarise: the current stable version of 7-Zip (and older) does not take full advantage of more than 2 CPU/cores when compressing as 7z (only for Zip and BZip2), but version 9 (currently in beta) does. The command-line option for using 16 cores with version 9 is (this is in the installation folder for the Windows version, in the help file, 7-zip.chm, Command Line Version/Switches/-m (Set compression Method)/<near> "Sets multithread mode"):

-mt16
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I don't think the summary is quite accurate, see some of the other answers for more details... –  rogerdpack Dec 10 '12 at 16:23
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3 Answers

up vote 6 down vote accepted

You have to use the beta version to get access for more cores. Beta is like stable at other softwares, don't worry about it. There was an explanation in a forum post on the official site. I'm using it for a while already, and there is no problem with it.

First

Second

By the way I'm using 7z 9.13 beta x64 at the minute. Using it on productive environments also, awesomeness. (Thanks Igor for the great software. ;))

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Since then, a new stable version came out, which supports multi-threaded compression by default, no need for the beta release. –  Shiki Jan 8 '12 at 22:41
    
That's not correct. It can use 4, 8, and more cores. Just use the latest version. Gosh. –  Shiki Jan 10 '12 at 20:08
    
See:noob.hu/2012/01/10/7z.png –  Shiki Jan 10 '12 at 20:09
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Note that this answer uses LZMA2 and not LZMA. LZMA2 can use more than two cores by splitting the file into chunks and independently processing them. This can result in LZMA offering higher compression ratios. –  Louis Nov 5 '12 at 8:22
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While creating a 7-Zip file it can use two threads, while creating a ZIP file it can use eight threads (on my eight-core machine).

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You can use 7z with LZMA2 method to use maximum cores –  ray pixar Jun 16 '13 at 13:29
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According to the Wikipedia article:

Features 7-Zip supports many features, including:

  1. Support for the 256-bit AES cipher. Encryption can be enabled for both files and the 7z directory structure. When the directory structure is encrypted, users are required to supply a password to see the filenames contained within the archive, unless only the data was encrypted but not the filenames. WinZip-developed AES encryption standard is also available in 7-Zip to encrypt ZIP archives with AES 256-bit, but it doesn't offer filename encryption as in 7z archives.
  2. Volumes of dynamically variable sizes, allowing use for backups on removable media such as writable CDs and DVDs.
  3. Usability as a basic orthodox file manager when used in 2-panel mode.
  4. Multiple CPU / core / threading settings can be configured.
  5. The ability to attempt to open EXE files as archives, allowing the decompression of data from inside many "SetUp" or "Installer" or "Extract" type programs without having to launch them.
  6. The ability to unpack archives with corrupted filenames, renaming the files as required. The ability to create self-extracting archives although cannot do so for multi-volume archives.

So open up the application and see what multi-threading is supported.

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I think it is more helpful than the unlock password protected PDF file answer. –  ta.speot.is May 17 '10 at 10:23
    
Flagged that already. Makes no sense at all here. (Or am I the lost lamb here? oO) –  Shiki May 17 '10 at 10:34
    
I have flagged it to. I could edit it to blankness but I can't delete the actual post, so I'm leaving it alone. –  ta.speot.is May 17 '10 at 10:39
    
if there's something truly offensive or abusive, feel free to edit it out of a post (replace with [this content deleted because blah] or something), but in this case flagging as spam and leaving it for moderators was the right thing to do, thanks. –  quack quixote May 17 '10 at 20:02
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re: RTFM. be nice. posting quotes (from a Wikipedia article or product documentation) that clarify a situation is good. chiding the user for not reading is RUDE AND UNNECESSARY. i'm editing your post to remove such; in the future, please leave such comments out. –  quack quixote May 17 '10 at 20:05
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