On Sunday, 14 October 2018 at 11:36:28 UTC, notna wrote:
Hi D gurus.
Did read an interesting post form GitLab [1] how they improved
performance by 30x by just going to go_v1.9... because they
again went from "fork" to "posix_spawn"...
[1]
https://about.gitlab.com/2018/01/23/how-a-fix-in-go-19-sped-up-our-gitaly-service-by-30x/
Hi notna,
Thanks for the interesting article.
I've searched the GitHub DLANG org for "posix_spawn" and didn't
find a hit...
Indeed currently (as of DMD 2.082.1) druntime does not include
bindings of posix_spawn [1]. The nice thing about D is that if
you need to use a C function that's not yet declared in druntime
it's very easy to add the declaration to your app and use it.
I looked at glibc's implementation and translated the
declarations. You can find them along with the example from the
man page here:
https://run.dlang.io/gist/ZombineDev/536eb8b456cc365b7ee05133ec452627?compiler=dmd
(if you want to use posix_spawn in your app/library copy the code
from line 133 till the end of the file).
so asking myself and you.... is DLANG still on "fork" and could
there be some performance improvement potential?
One cannot say whether D is "on fork" or not because unlike Go,
everyone is free to use whatever system function they need,
without explicit cooperation from upstream. Though probably many
apps or libraries use the high-level functions declared in
https://dlang.org/phobos/std_process instead of using the
low-level system functions directly. In particular, spawnProcess
[2] is currently implemented via fork/exec. I found an open issue
about optimizing std.process:
https://issues.dlang.org/show_bug.cgi?id=14770.
I'll look into making a pull request to druntime about
posix_spawn, though no promises for phobos, as there the code is
a bit more involved and would need more careful analysis.
[1]: http://man7.org/linux/man-pages/man3/posix_spawn.3.html
[2]: https://dlang.org/phobos/std_process#.spawnProcess
