On 11/04/2021 09:26, SZEDER Gábor wrote:
On Fri, Apr 09, 2021 at 06:47:23PM +0000, Andrzej Hunt via GitGitGadget wrote:
From: Andrzej Hunt <ajrhunt@xxxxxxxxxx>
fill_bloom_key() allocates memory into bloom_key, we need to clean that
up once the key is no longer needed.
This fixes the following leak which was found while running t0002-t0099.
Although this leak is happening in code being called from a test-helper,
the same code is also used in various locations around git, and could
presumably happen during normal usage too.
It does indeed happen: 'git commit-graph write --reachable
--changed-paths' generates Bloom filters for every commit, with each
filter containing all paths modified by its associated commit, so it
leaks a lot of 7 * 4byte hashes. This patch reduces the memory usage
of that command:
Max RSS
before after
---------------------------------------------
android-base 1275028k 1006576k -21.1%
chromium 3245144k 3127764k -3.6%
cmssw 793996k 699156k -12.0%
cpython 371584k 343480k -7.6%
elasticsearch 748104k 637936k -14.7%
freebsd-src 819020k 741272k -9.5%
gcc 867412k 730332k -15.8%
gecko-dev 2619112k 2457280k -6.2%
git 252684k 216900k -14.2%
glibc 239000k 222228k -7.0%
go 264132k 251344k -4.9%
homebrew-cask 542188k 480588k -11.4%
homebrew-core 805332k 715848k -11.1%
jdk 417832k 342928k -17.9%
libreoff-core 1257296k 1089980k -13.3%
linux 2033296k 1759712k -13.5%
llvm-project 1067216k 956704k -10.4%
mariadb-srv 695172k 559508k -19.5%
postgres 340132k 317416k -6.7%
rails 325432k 294332k -9.6%
rust 655244k 584904k -10.7%
tensorflow 507308k 480848k -5.2%
webkit 2466812k 2237332k -9.3%
Just out of curiosity, I disabled the questionable hardcoded 512 paths
limit on the size of modified path Bloom filters, and the memory usage
in the jdk repository sunk by over 55%, from 849520k to 379760k.
Please feel free to include any of the above data points in the commit
message.
Thank you for the detailed analysis - these kinds of results are very
motivating! I will include a brief summary (something like "10% typical
improvement for 'commit-graph write' for large repos") along with a link
to your posting for those who want the full picture.
