How often should you use git-gc

Question

How often should you use git-gc     The manual page simply says      Users are encouraged to run this task on a regular basis within each repository to maintain good disk space utilization and good operating performance    Are there some commands to get some object counts to find out whether it s time to gc

User · Answer

If you re using Git-Gui  it tells you when you should worry    This repository currently has approximately 1500 loose objects     The following command will bring a similar number     git count-objects   Except  from its source  git-gui will do the math by itself  actually counting something at  git objects folder and probably brings an approximation  I don t know tcl to properly read that     In any case  it seems to give the warning based on an arbitrary number around 300 loose objects

User · Answer

It depends mostly on how much the repository is used   With one user checking in once a day and a branch merge etc operation once a week you probably don t need to run it more than once a year   With several dozen developers working on several dozen projects each checking in 2-3 times a day  you might want to run it nightly   It won t hurt to run it more frequently than needed  though   What I d do is run it now  then a week from now take a measurement of disk utilization  run it again  and measure disk utilization again   If it drops 5  in size  then run it once a week   If it drops more  then run it more frequently   If it drops less  then run it less frequently

User · Answer

This quote is taken from  Version Control with Git  Git runs garbage collection automatically      If there are too many loose objects in the repository     When a push to a remote repository happens     After some commands that might introduce many loose objects     When some commands such as  git reflog expire explicitly request it And finally  garbage collection occurs when you explicitly request it using the  git gc command  But when should that be  There   s no solid answer to this question  but there is some good advice and best practice  You should consider running  git gc manually in a few situations      If you have just completed a  git filter-branch   Recall that filter-branch rewrites many commits  introduces new ones  and leaves the old ones on a  ref that should be removed when you are satisfied with the results  All those dead objects  that are no longer referenced since you just removed the one  ref pointing to them  should be removed via garbage collection      After some commands that might introduce many loose objects  This might be a large rebase effort  for example  And on the flip side  when should you be wary of garbage collection      If there are orphaned refs that you might want to recover     In the context of  git rerere and you do not need to save the resolutions forever     In the context of only tags and branches being sufficient to cause Git to retain a commit permanently     In the context of  FETCH HEAD retrievals  URL-direct retrievals via git fetch   because they are immediately subject to garbage collection

User · Answer

Drop it in a cron job that runs every night  afternoon   when you re sleeping

User · Answer

Recent versions of git run gc automatically when required  so you shouldn t have to do anything  See the Options section of man git-gc 1    Some git commands run git gc --auto after performing operations that could create many loose objects

User · Answer

I use git gc after I do a big checkout  and have a lot of new object  it can save space  E g  if you checkout a big SVN project using git-svn  and do a git gc  you typically save a lot of space

User · Answer

You can do it without any interruption  with the new  Git 2 0 Q2 2014  setting gc autodetach   See commit 4c4ac4d and commit 9f673f9  Nguy n Th  i Ng c Duy  aka pclouds       gc --auto takes time and can block the user temporarily  but not any less annoyingly     Make it run in background on systems that support it    The only thing lost with running in background is printouts  But gc output is not really interesting    You can keep it in foreground by changing gc autodetach      Since that 2 0 release  there was a bug though  git 2 7  Q4 2015  will make sure to not lose the error message  See commit 329e6e8  19 Sep 2015  by Nguy n Th  i Ng c Duy  pclouds    Merged by Junio C Hamano -- gitster -- in commit 076c827  15 Oct 2015        gc  save log from daemonized gc --auto and print it next time      While commit 9f673f9  gc  config option for running --auto in background - 2014-02-08  helps reduce some complaints about  gc --auto  hogging the terminal  it creates another set of problems       The latest in this set is  as the result of daemonizing  stderr is closed and all warnings are lost  This warning at the end of cmd gc   is particularly important because it tells the user how to avoid  gc --auto  running repeatedly    Because stderr is closed  the user does not know  naturally they complain about  gc --auto  wasting CPU       Daemonized gc now saves stderr to  GIT DIR gc log    Following gc --auto will not run and gc log printed out until the user removes gc log

User · Answer

I use when I do a big commit  above all when I remove more files from the repository   after  the commits are faster

User · Answer

Note that the downside of garbage-collecting your repository is that  well  the garbage gets collected  As we all know as computer users  files we consider garbage right now might turn out to be very valuable three days in the future  The fact that git keeps most of its debris around has saved my bacon several times     by browsing all the dangling commits  I have recovered much work that I had accidentally canned   So don   t be too much of a neat freak in your private clones  There   s little need for it   OTOH  the value of data recoverability is questionable for repos used mainly as remotes  eg  the place all the devs push to and or pulled from  There  it might be sensible to kick off a GC run and a repacking frequently

User · Answer

You don t have to use git gc very often  because git gc  Garbage collection  is run automatically on several frequently used commands   git pull git merge git rebase git commit   Source  git gc best practices and FAQS

[git] How often should you use git-gc?

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