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Re: [jgit-dev] Creating new refs on a repository with 100k packed-refs is slow
|
> On 6 Oct 2020, at 20:16, kaushikl@xxxxxxxxxxxxxx wrote:
>
> Hi,
>
> We have noticed that creating a new ref takes ~600ms on a repository with around 100k packed-refs.
>
> My test repository:
>
> $ git count-objects -v
> count: 0
> size: 0
> in-pack: 100042
> packs: 1
> size-pack: 9734
> prune-packable: 0
> garbage: 0
> size-garbage: 0
>
> $ find refs/ -type f | wc -l
> 0
>
> Specs:
>
> Machine has 32 cores and 250G RAM.
>
> $ uname -r
> 4.4.0-165-generic
>
> $ lsb_release -a
> No LSB modules are available.
> Distributor ID: Ubuntu
> Description: Ubuntu 16.04.6 LTS
> Release: 16.04
> Codename: xenial
>
> Jgit version is 5.9
>
> $ java -version
> openjdk version "1.8.0_242"
> OpenJDK Runtime Environment (build 1.8.0_242-8u242-b08-0ubuntu3~16.04-b08)
> OpenJDK 64-Bit Server VM (build 25.242-b08, mixed mode)
>
> Consider a small program[1] which creates a ref 'simple'. On executing the program on my test repository, I see output:
>
> simple: 677 ms
>
> This seems slow. Is this expected behavior with jgit?
Can you share the generated .gitconfig?
(When you use JGit on a filesystem, it performs the computation of the filesystem latency)
Is this a local disk or a mounted NFS share?
SSD or spinning?
Luca.
>
>
>
> [1]
> package test;
>
> import java.io.File;
> import java.io.IOException;
> import java.util.concurrent.TimeUnit;
>
> import org.eclipse.jgit.api.Git;
> import org.eclipse.jgit.api.errors.GitAPIException;
> import org.eclipse.jgit.lib.Repository;
> import org.eclipse.jgit.revwalk.RevCommit;
> import org.eclipse.jgit.revwalk.RevWalk;
>
> public class Test {
> public static void main(String[] args) {
> try {
> String path = null;
> if (args.length == 1) {
> path = args[0];
> } else {
> System.out.println("Repo path must be specified.");
> System.exit(1);
> }
> String branch = "simple";
> try (Git git = Git.open(new File(path))) {
> Repository repo = git.getRepository();
> RevWalk walk = new RevWalk(repo);
> RevCommit commit = walk.parseCommit(repo.exactRef("refs/heads/master").getObjectId());
> long startTimeInNanoSecs = System.nanoTime();
> git.branchCreate().setName(branch).setStartPoint(commit).call();
> long estimatedTimeInNanoSecs = System.nanoTime() - startTimeInNanoSecs;
> System.out.println(branch + ": " + TimeUnit.NANOSECONDS.toMillis(estimatedTimeInNanoSecs) + " ms");
> }
> } catch (IllegalStateException | GitAPIException | IOException e) {
> e.printStackTrace();
> }
> }
> }
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