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Comments (115)

• adsharma
  > We plan to deliver improvements to [..] purging mechanismsDuring my time at Facebook, I maintained a bunch of kernel patches to improve jemalloc purging mechanisms. It wasn't popular in the kernel or the security community, but it was more efficient on benchmarks for sure.Many programs run multiple threads, allocate in one and free in the other. Jemalloc's primary mechanism used to be: madvise the page back to the kernel and then have it allocate it in another thread's pool.One problem: this involves zero'ing memory, which has an impact on cache locality and over all app performance. It's completely unnecessary if the page is being recirculated within the same security domain.The problem was getting everyone to agree on what that security domain is, even if the mechanism was opt-in.https://marc.info/?l=linux-kernel&m=132691299630179&w=2
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  bmenrigh
  I recently started using Microsoft's mimalloc (via an LD_PRELOAD) to better use huge (1 GB) pages in a memory intensive program. The performance gains are significant (around 20%). It feels rather strange using an open source MS library for performance on my Linux system.There needs to be more competition in the malloc space. Between various huge page sizes and transparent huge pages, there are a lot of gains to be had over what you get from a default GNU libc.
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  apatheticonion
  As an Australian who was just made redundant from a role that involved this type of low level programming - I love working on these these kinds of challenges.I'm saddened that the job market in Australia is largely React CRUD applications and that it's unlikely I will find a role that lets me leverage my niche skill set (which is also my hobby)
• dang
  Related. Others?Jemalloc Postmortem - https://news.ycombinator.com/item?id=44264958 - June 2025 (233 comments)Jemalloc Repositories Are Archived - https://news.ycombinator.com/item?id=44161128 - June 2025 (7 comments)
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  bfgeek
  One has to wonder if this due to the global memory shortage. ("Oh - changing our memory allocator to be more efficient will yield $XXM dollar savings over the next year").
• jjuliano
  I remember I was a senior lead softeng of a worldbank funded startup project, and have deployed Ruby with jemalloc in prod. There's a huge noticeable speed and memory efficiency. It did saved us a lot of AWS costs, compare to just using normal Ruby. This was 8 years ago, why haven't projects adopt it yet as de facto.
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  RegnisGnaw
  Is there a concise timelime/history of this? I thought jemalloc was 100% open source, why is Meta in control of it?
• joelsiks
  Opening up strong with a gigantic merge of the stuff they've been working on in their own fork: https://github.com/jemalloc/jemalloc/pull/2863
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  jshorty
  Surprised not to see any mention of the global memory supply shock. Would love to learn more about how that economic is shifting software priorities toward memory allocation for the first time in my (relatively young) career
• rishabhjajoriya
  Large engineering orgs often underestimate how much CI pipelines amplify performance issues. Even small inefficiencies multiply when builds run hundreds of times a day.
• anon
  undefined
• nubinetwork
  Someone should tell Bryan Cantrill, he'd probably be ecstatic...
• pram
  I used jemalloc recently for ComfyUI/Wan and it’s literally magic. I’m surprised it doesn’t come that way by default.
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  starkparker
  (wrong thread)
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  thatoneengineer
  First impressions: LOL, the blunt commentary in the HN thread title compared to the PR-speak of the fb.com post.Second thoughts: Actually the fb.com post is more transparent than I'd have predicted. Not bad at all. Of course it helps that they're delivering good news!
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  xxs
  Few months back, some of the services switched to jemalloc for the Java VM. It took months (of memory dumps and tracing sys-calls) to blame the JVM, itself, for getting killed by the oom_killer.Initially the idea was diagnostics, instead the the problem disappeared on its own.
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  markstos
  How is the original author making out in the new arrangement?
• lobf
  >We are committed to continuing to develop jemalloc developmentFrom the Department of Redundancy Department.
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  flykespice
  Jemalloc also is used by android bionic libc library
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  charcircuit
  Meta never abandoned jemalloc. https://github.com/facebook/jemalloc remained public the entire time. It's my understanding that Jason Evans, the creator of jemalloc, had ownership over the jemalloc/jemalloc repo which is why that one stopped being updated after he left.
• m3kw9
  All the AI investment and their biggest news is commitment to Jemalloc
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  fermentation
  Seems like they’d want to wait to commit until after the layoffs, right?
• rgupta1833
  [dead]
• anon
  undefined
• lesscraft
  [dead]
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  oncallthrow
  And the Oscar for most mealy-mouthed post of the year goes to…
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  carlos256
  If you need to optimize the allocator you are doing it wrong.
• Nuzzerino
  > Building a software system is a lot like building a skyscraper: The product everyone sees is the top, but the part that keeps it from falling over is the foundation buried in the dirt and the scaffolding hidden from sight.They should have just called it an ivory tower, as that's what they're building whenever they're not busy destroying democracy with OS Backdoor lobbyism or Cambridge Analytica shenanigans.Edit: If every thread about any of Elon Musk's companies can contain at least 10 comments talking about Elon's purported crimes against humanity, threads about Zuckerberg's companies can contain at least 1 comment. Without reminders like this, stories like last week's might as well remain non-consequential.