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[104.178.186.189]) by smtp.gmail.com with ESMTPSA id y11-20020a05620a44cb00b006a37eb728cfsm7939593qkp.1.2022.06.29.10.21.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 29 Jun 2022 10:21:15 -0700 (PDT) Date: Wed, 29 Jun 2022 13:21:14 -0400 From: Taylor Blau To: Gregory Szorc Cc: git@vger.kernel.org, stolee@gmail.com Subject: Re: Race condition between repack and loose-objects maintenance task Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Wed, Jun 29, 2022 at 10:16:38AM -0700, Gregory Szorc wrote: > > In either case, my recommendation would be to keep those unreachable > > objects which haven't yet aged out of the repository around for longer, > > which will decrease the likelihood of seeing the race. > > We had to lower gc.pruneExpire from its default of 1 hour because > otherwise this would result in the creation of thousands of loose > objects. This is normally acceptable. However, on NFS, the churn from > lots of file creation and deletion resulted in acceptable performance > degradation. We had to lower gc.pruneExpire to minimize the damage. Makes sense. Having a shorter gc.pruneExpire makes the race much more likely to occur in practice, so I'm glad that we have a plausible confirmation that that's what's going on in your repository. > > See Documentation/technical/cruft-packs.txt for more information about > > cruft packs. > > Yes, I saw this new feature in the Git release this week and am hoping > to roll it out to better mitigate this general problem! With cruft > packs, I anticipate being able to restore a longer gc.pruneExpire > value as they should mitigate the NFS performance badness we're > working around. Thank you for confirming it should help with the > problem. That should definitely help. Let me know if you have any questions, and thanks for trying it out! Thanks, Taylor