51–60 of 273 posts
How was the flame graph created? (Not very familiar with C and the performance tools around it)
It will spin up a localhost server after the trace ends, the profiler uses the localhost server and nothing is shared with Firefox servers unless you explicitly choose to upload the data and create a permalink.
48 hours is a crazy amount of time to spend just to compress a git folder, it's only a couple GB. 41 minutes still seems like quite a long time. Why aren't they just snapshotting and archiving the full git repo? Does `git bundle` add something over frequent ZFS backups?
> Be aware that even with these recommendations, syncing in this way has some risk since it bypasses Git’s normal integrity checking for repositories, so having backups is advised. You may also wish to do a git fsck to verify the integrity of your data on the destination system after syncing. https://git-scm.com/docs/gitfaq#_transfers It doesn't tell you how to make a backup safely though. On a personal scale, Syncth…
IME, it has always turned out to be the correct decision to eliminate any n^2 operation in anything I’ve written. I don’t write exotic algorithms, but it’s always astounding how small n needs to be to become observably problematic.
48 hours is a crazy amount of time to spend just to compress a git folder, it's only a couple GB. 41 minutes still seems like quite a long time. Why aren't they just snapshotting and archiving the full git repo? Does `git bundle` add something over frequent ZFS backups?
zfs snapshots are difficult to offsite in non-zfs replicas, say like an S3 bucket. That said, there's another less known feature that bundles help out with when used with `git clone --bundle-uri` The client can specify a location to a bundle, or the server can send the client the bundle location in the clone results and the client can fetch the bundle, unpack it, and then update the delta via the git server, so it's…
"fixed it with an algorithmic change, reducing backup times exponentially" If the backup times were O(n^2), are they now O(n^2 / 2^n)? I would guess not.
This is not the precise mathematical definition of exponential, but rather the colloquial one, where it just means "a lot".
IME, it has always turned out to be the correct decision to eliminate any n^2 operation in anything I’ve written. I don’t write exotic algorithms, but it’s always astounding how small n needs to be to become observably problematic.
My rule of thumb for 80%-90% of the problems is, if you need complicated algorithm, it means your data model isn't right. Sure, you do need complicated algorithms for compilers, db internals, route planning et all, but all things considered, those are minority of the use cases.
> What this means for GitLab customers — [a bunch of stuff about how customers can now back up more frequently and more robustly] Realtalk: They should rewrite this post's headline to be in a positive tense instead of leading with a negative word. I'm glad I read the post, because it is a cool and good fix, but I saw “Decreasing […] repo backup” and my first thought was that it was an announcement of some service dow…
Here comes an unpopular nitpick: "... we traced the issue to a 15-year-old Git function with O(N²) complexity and fixed it with an algorithmic change, reducing backup times exponentially." Uh no you didn't. Not possible. At most a polynomial reduction is possible else complexity theory needs a re-write. (OK, yes, k could be doing some heavy lifting here, but I doubt it.) If you are going to quote a maths formula then…
OP here. Feedback is always welcome, I did mean exponentially in the colloquial sense. I do see how it is confusing here, will change it.
If my barista says that his new coffee is exponentially better, it’s ok to use it colloquially.
If my git hosting provider writes about an impactful performance improvement, it’s not.
Earlier quoted context omitted.
Meaningless and non-constructive pedantry.
I disagree. Misuse of the word "exponential" is a major pet peeve of mine. It's a particular case of the much more common "use mathematically precise phrasing to sound careful/precise" that you often find in less than honest writing. Here they are actually using it to refer to growth functions (which is rare for this error) and being honest (which is also rare IMO) but it's still wrong. They should have written about…
I'm confused why you wouldn't simply snapshot the block-level device if the protocol of the information on top is going to cause this much headache. Quiescing git operations for block level activity is probably not trivial, but it sounds like an easier problem to solve to me. This is the approach I've taken with SQLite in production environments. Turn on WAL and the problem gets even easier to solve. Customer configu…