otp
glibc
Our great sponsors
otp | glibc | |
---|---|---|
23 | 45 | |
11,041 | 1,203 | |
1.2% | 4.6% | |
10.0 | 9.8 | |
1 day ago | 9 days ago | |
Erlang | C | |
Apache License 2.0 | GNU General Public License v3.0 or later |
Stars - the number of stars that a project has on GitHub. Growth - month over month growth in stars.
Activity is a relative number indicating how actively a project is being developed. Recent commits have higher weight than older ones.
For example, an activity of 9.0 indicates that a project is amongst the top 10% of the most actively developed projects that we are tracking.
otp
-
Install mutiple Erlang and Elixir with vfox
Theoretically, you could install any version that appears in https://github.com/erlang/otp/releases. Since it is compiled and installed from source, the installation process will take some time. When you see the following message, the installation is complete.
-
Perfect Elixir: Environment Setup
I’m on MacOS and erlang.org, elixir-lang.org, and postgresql.org all suggest installation via Homebrew, which is a very popular package manager for MacOS.
- Scheduling Internals
- Epoll: The API that powers the modern internet (2022)
-
Elixir v1.15 released
You can read my original report and subsequent PRs in Erlang/OTP here: https://github.com/erlang/otp/issues/5811
-
Open Sourcing Erlfuzz
- a massive speedup of a common static analyzer for Erlang (https://github.com/erlang/otp/pull/5997)
-
Why are there so many languages?
Funny that you should mention Erlang. Looking at the Github for Erlang, it appears that the source for Erlang is 16.8% written in C. I would bet these are not the least important bits of the whole thing. So, Erlang depends on C.
-
Erlang: More Optimizations in the Compiler and JIT
It looks more like some of the JIT improvements made it profitable to manually unroll some loops in the base64 module: https://github.com/erlang/otp/commit/a03cf1601605dee767cd9d5...
-
Mixing sync and async views in the same application
https://github.com/erlang/otp as far as I know. It's somewhat confusing and I honestly couldn't say exactly where the BEAM VM or OTP or ERTS (Erlang Runtime System) start and end. I've never dug into it. I just install Elixir and sometimes Erlang through the ASDF tool, which does all the compiling for me.
- When people send a https request to my custom web server, it crashes the entire system. How do I fortify my system not to accept em?
glibc
- I cut GTA Online loading times by 70% (2021)
-
Cray-1 performance vs. modern CPUs
I wonder if you’re using a different definition of ‘vectorized’ from the one I would use. For example glibc provides a vectorized strlen. Here is the sse version: https://github.com/bminor/glibc/blob/master/sysdeps/x86_64/m...
It’s pretty simple to imagine how to write an unoptimized version: read a vector from the start of the string, compare it to 0, convert that to a bitvector, test for equal to zero, then loop or clz and finish.
I would call this vectorized because it operates on 16 bytes (sse) at a time.
There are a few issues:
1. You’re still spending a lot of time in the scalar code checking loop conditions.
2. You’re doing unaligned reads which are slower on old processors
3. You may read across a cache line forcing you to pull a second line into cache even if the string ends before then.
4. You may read across a page boundary which could cause a segfault if the next page is not accessible
So the fixes are to do 64-byte (ie cache line) aligned accesses which also means page-aligned (so you won’t read from a page until you know the string doesn’t end in the previous page). That deals with alignment problems. You read four vector registers at a time but this doesn’t really cost much more if the string is shorter as it all comes from one cache line. Another trick in the linked code is that it first finds the cache line by reading the first 16 bytes then merging in the next 3 groups with unsigned-min, so it only requires one test against a zero vector instead of 4. Then it finds the zero in the cache line. You need to do a bit of work in the first iteration to become aligned. With AVX, you can use mask registers on reads to handle that first step instead.
-
Setenv Is Not Thread Safe and C Doesn't Want to Fix It
That was also my thought. To my knowledge `/etc/localtime` is the creation of Arthur David Olson, the founder of the tz database (now maintained by IANA), but his code never read `/etc/localtime` multiple times unless `TZ` environment variable was changed. Tzcode made into glibc but Ulrich Drepper changed it to not cache `/etc/localtime` when `TZ` is unset [1]; I wasn't able to locate the exact rationale, given that the commit was very ancient (1996-12) and no mailing list archive is available for this time period.
[1] https://github.com/bminor/glibc/commit/68dbb3a69e78e24a778c6...
-
CTF Writeup: Abusing select() to factor RSA
That's not really what the problem is. The actual code is fine.
The issue is that the definition of `fd_set` has a constant size [1]. If you allocate the memory yourself, the select() system call will work with as many file descriptors as you care to pass to it. You can see that both glibc [2] and the kernel [3] support arbitrarily large arrays.
[1] https://github.com/bminor/glibc/blob/master/misc/sys/select....
[2] https://github.com/bminor/glibc/blob/master/sysdeps/unix/sys...
[3] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/lin...
-
How are threads created in Linux x86_64
The source code for that is here.
-
Using Uninitialized Memory for Fun and Profit (2008)
Expanding macro gives three GCC function attributes [2]: `__attribute__ ((malloc))`, `__attribute__ ((alloc_size(1)))` and `__attribute__ ((warn_unused_result))`. They are required for GCC (and others recognizing them) to actually ensure that they behave as the standard dictates. Your own malloc-like functions won't be treated same unless you give similar attributes.
[1] https://github.com/bminor/glibc/blob/807690610916df8aef17cd1...
[2] https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attribute...
-
“csinc”, the AArch64 instruction you didn’t know you wanted
IFunc relocations is what enables glibc to dynamically choose the best memcpy routine to use at runtime based on the CPU.
see https://github.com/bminor/glibc/blob/glibc-2.31/sysdeps/x86_...
-
memmove() implementation in strictly conforming C -- possible?
memmove can be very well implemented in pure C, libc implementations usually have a "generic" (meaning, architecture independent) fallback. Here is musl generic implementation and its x86-64 assembly implementation. For glibc, implementation is a bit more complex, having multiple architectures implemented, but you could find a generic implementation with these two files: memmove.c and generic/memcopy.h.
-
Fedora 38 LLVM vs. Team Fortress 2
Yeah, looks like the Q_strcat(pszContentPath, "/"); is invalid, as glibc has only allocated exactly enough to fit the path in the buffer returned by realpath().
Interestingly, the open group spec says that a null argument to realpath is "Implementation defined" [0]
And the linux (glibc) man pages say it allocates a buffer "Up to PATH_MAX" [1]
I guess "strlen(path)" is "Up to PATH_MAX", but the man page seems unclear - you could read that as implying the buffer is always allocated to PATH_MAX size, but that's not what seems to be happening, just effectively calling strdup() [2]. I have no idea how to feed back to the linux man pages, but might be worth clarifying there.
[0] https://pubs.opengroup.org/onlinepubs/009696799/functions/re...
[1] https://linux.die.net/man/3/realpath
[2] https://github.com/bminor/glibc/blob/0b9d2d4a76508fdcbd9f421...
-
Method implementations
For the actual sources you will have to look at one of the mirrors of the C standard library, such as https://github.com/bminor/glibc/tree/master/sysdeps/ieee754/dbl-64
What are some alternatives?
protoactor-go - Proto Actor - Ultra fast distributed actors for Go, C# and Java/Kotlin
musl - Unofficial mirror of etalabs musl repository. Updated daily.
Elixir - Elixir is a dynamic, functional language for building scalable and maintainable applications
cosmopolitan - build-once run-anywhere c library
calypso - Calypso is a mostly imperative language with some functional influences that is focused on flexibility and simplicity.
dns - DNS library in Go
scryer-prolog - A modern Prolog implementation written mostly in Rust.
0.30000000000000004 - Floating Point Math Examples
caramel - :candy: a functional language for building type-safe, scalable, and maintainable applications
json-c - https://github.com/json-c/json-c is the official code repository for json-c. See the wiki for release tarballs for download. API docs at http://json-c.github.io/json-c/
cdk-emqx-cluster
degasolv - Democratize dependency management.