blog/vlang-update: tombstone post
This commit is contained in:
parent
956b930965
commit
78bcfcfd98
|
|
@ -1,260 +1,9 @@
|
|||
---
|
||||
title: V Update - June 2020
|
||||
title: [removed]
|
||||
date: 2020-06-17
|
||||
series: v
|
||||
---
|
||||
|
||||
# V Update - June 2020
|
||||
This post has been removed. I will learn from my mistakes that lead to this post
|
||||
being authored and published.
|
||||
|
||||
Every so often I like to check in on the [V Programming Language][vlang]. It's been
|
||||
about six months since [my last post](https://christine.website/blog/v-vvork-in-progress-2020-01-03),
|
||||
so I thought I'd take another look at it and see what progress has been done in six
|
||||
months.
|
||||
|
||||
[vlang]: https://vlang.io
|
||||
|
||||
Last time I checked, V 0.2 was slated for release in December 2019. It is currently
|
||||
June 2020, and the latest release (at time of writing) is [0.1.27][vrelease0127].
|
||||
|
||||
## Feature Update
|
||||
|
||||
Interestingly, the V author seems to have walked back one of their original
|
||||
listed features of V and now has an [abstract syntax tree][ast] for representing the
|
||||
grammar of the language. They still claim that functions are "pure" by default, but
|
||||
allow functions to perform print statements while still being "pure". Printing data
|
||||
to standard out is an impure side effect, but if you constrain the definition of
|
||||
"side effects" to only include mutability of memory, this could be fine.
|
||||
|
||||
[vrelease0127]: https://github.com/vlang/v/releases/tag/0.1.27
|
||||
[ast]: https://github.com/vlang/v/commit/093a025ebfe4f0957d5d69ad4ddcdc905a6d7b81#diff-5adb689a65970037f7f0ced3d4b9e800
|
||||
|
||||
The next stable release 0.2 seems to be planned for June 2020 (according to the readme);
|
||||
and according to the todo list in the repo, memory management seems to be one of the
|
||||
things that will be finished. V is also apparently in alpha, but will also apparently
|
||||
jump from alpha directly to stable?
|
||||
|
||||
## Build
|
||||
|
||||
Testing V is a bit more difficult for me now as its build process is incompatible
|
||||
with my Linux tower's [NixOS](https://nixos.org/nixos) install (I tend to try and
|
||||
package all the programs I use for testing this stuff so it is easier to reproduce
|
||||
my environment on other machines). The V scripts also do not work on my NixOS tower
|
||||
because it doesn't have a `/usr/local/bin`. The correct way to make a shell script
|
||||
cross-platform is to use the following header:
|
||||
|
||||
```sh
|
||||
#!/usr/bin/env v
|
||||
```
|
||||
|
||||
This makes the `env` program search for the V binary in your `$PATH`, and will
|
||||
function correctly on all platforms.
|
||||
|
||||
The Makefile in the V source tree seems to do
|
||||
network calls, specifically a `git clone`. Remember that this is on the front page
|
||||
of the website:
|
||||
|
||||
> V can be bootstrapped in under a second by compiling its code translated to C with a simple
|
||||
>
|
||||
> `cc v.c`
|
||||
>
|
||||
> No libraries or dependencies needed.
|
||||
|
||||
Git is a dependency, which means perl is a dependency, which means a shell is a
|
||||
dependency, which means glibc is a dependency, which means that a lot of other
|
||||
things (including posix threads) are also dependencies. Pedantically, you could even
|
||||
go as far as saying that you could count the Linux kernel, the processor being used
|
||||
and the like as dependencies, but that's a bit out of scope for this.
|
||||
|
||||
## Memory Management
|
||||
|
||||
> V doesn't use garbage collection or reference counting. The compiler cleans
|
||||
> everything up during compilation. If your V program compiles, it's guaranteed
|
||||
> that it's going to be leak free.
|
||||
|
||||
Amusingly, the documentation still claims that memory management is both a work in
|
||||
progress and has perfect accuracy for cleaning up things at compile time. Let's run
|
||||
my favorite test, the "how much ram do you leak compiling hello world" test. Last
|
||||
it leaked `4,600,383` bytes (or about 4.6 megabytes) and before that it leaked
|
||||
`3,861,785` bytes (or about 3.9 megabytes). This time:
|
||||
|
||||
```
|
||||
$ valgrind ./v hello.v
|
||||
==5413== Memcheck, a memory error detector
|
||||
==5413== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
|
||||
==5413== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info
|
||||
==5413== Command: ./v hello.v
|
||||
==5413==
|
||||
==5413==
|
||||
==5413== HEAP SUMMARY:
|
||||
==5413== in use at exit: 7,232,779 bytes in 163,690 blocks
|
||||
==5413== total heap usage: 182,696 allocs, 19,006 frees, 11,309,504 bytes allocated
|
||||
==5413==
|
||||
==5413== LEAK SUMMARY:
|
||||
==5413== definitely lost: 2,673,351 bytes in 85,739 blocks
|
||||
==5413== indirectly lost: 4,265,809 bytes in 77,711 blocks
|
||||
==5413== possibly lost: 256,000 bytes in 1 blocks
|
||||
==5413== still reachable: 37,619 bytes in 239 blocks
|
||||
==5413== suppressed: 0 bytes in 0 blocks
|
||||
==5413== Rerun with --leak-check=full to see details of leaked memory
|
||||
==5413==
|
||||
==5413== For counts of detected and suppressed errors, rerun with: -v
|
||||
==5413== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
|
||||
```
|
||||
|
||||
It seems that the memory managment really is a work in progress. This increase in
|
||||
leakage means that the compiler building itself now creates `7,232,779` bytes of
|
||||
leaked ram (which if i recall is actually a remarkable improvement).
|
||||
|
||||
However, `hello world` seems to leak again:
|
||||
|
||||
```
|
||||
$ valgrind ./hello
|
||||
==13258== Memcheck, a memory error detector
|
||||
==13258== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
|
||||
==13258== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info
|
||||
==13258== Command: ./hello
|
||||
==13258==
|
||||
hello world
|
||||
==13258==
|
||||
==13258== HEAP SUMMARY:
|
||||
==13258== in use at exit: 12,144 bytes in 14 blocks
|
||||
==13258== total heap usage: 15 allocs, 1 frees, 13,168 bytes allocated
|
||||
==13258==
|
||||
==13258== LEAK SUMMARY:
|
||||
==13258== definitely lost: 0 bytes in 0 blocks
|
||||
==13258== indirectly lost: 0 bytes in 0 blocks
|
||||
==13258== possibly lost: 0 bytes in 0 blocks
|
||||
==13258== still reachable: 12,144 bytes in 14 blocks
|
||||
==13258== suppressed: 0 bytes in 0 blocks
|
||||
==13258== Rerun with --leak-check=full to see details of leaked memory
|
||||
==13258==
|
||||
==13258== For counts of detected and suppressed errors, rerun with: -v
|
||||
==13258== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
|
||||
```
|
||||
|
||||
I'm not entirely sure how this happened, but here is the output of
|
||||
`v -keepc hello.v`: https://git.io/Jfdsu.
|
||||
|
||||
## Doom
|
||||
|
||||
The [Doom](https://github.com/vlang/doom) translation project still has one file
|
||||
translated (and apparently it breaks sound effects but not music).
|
||||
|
||||
## 1.2 Million Lines of Code
|
||||
|
||||
Let's re-run the artificial as heck 1.2 million lines of code benchmark from the
|
||||
last post:
|
||||
|
||||
```
|
||||
$ bash -c 'time ~/code/v/v main.v'
|
||||
|
||||
real 7m54.847s
|
||||
user 7m32.860s
|
||||
sys 0m14.212s
|
||||
```
|
||||
|
||||
This is a major improvement! It's cut at least 2 minutes off of the build time for
|
||||
this incredibly contrived benchmark! Let's see how big the generated binary is:
|
||||
|
||||
```
|
||||
$ du -hs ./main
|
||||
179M ./main
|
||||
```
|
||||
|
||||
This is identical to how big it was last time. Let's see how much ram it leaks:
|
||||
|
||||
```
|
||||
$ valgrind ./main
|
||||
==11773== Memcheck, a memory error detector
|
||||
==11773== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
|
||||
==11773== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info
|
||||
==11773== Command: ./main
|
||||
==11773==
|
||||
hello, 1 1!
|
||||
<snipped>
|
||||
==11773==
|
||||
==11773== HEAP SUMMARY:
|
||||
==11773== in use at exit: 12,144 bytes in 14 blocks
|
||||
==11773== total heap usage: 15 allocs, 1 frees, 13,168 bytes allocated
|
||||
==11773==
|
||||
==11773== LEAK SUMMARY:
|
||||
==11773== definitely lost: 0 bytes in 0 blocks
|
||||
==11773== indirectly lost: 0 bytes in 0 blocks
|
||||
==11773== possibly lost: 0 bytes in 0 blocks
|
||||
==11773== still reachable: 12,144 bytes in 14 blocks
|
||||
==11773== suppressed: 0 bytes in 0 blocks
|
||||
==11773== Rerun with --leak-check=full to see details of leaked memory
|
||||
==11773==
|
||||
==11773== For counts of detected and suppressed errors, rerun with: -v
|
||||
==11773== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
|
||||
```
|
||||
|
||||
About what I expected.
|
||||
|
||||
## Concurrency
|
||||
|
||||
A common problem that shows up when writing multi-threaded code are
|
||||
[race conditions][races]. Effectively, race conditions are when two bits of code try
|
||||
to do the same thing at the same time on the same block of memory. This leads to
|
||||
undefined behavior, which is bad because it can corrupt or crash programs.
|
||||
|
||||
[races]: https://en.wikipedia.org/wiki/Race_condition
|
||||
|
||||
As an example, consider this program `raceanint.v`:
|
||||
|
||||
```
|
||||
fn main() {
|
||||
foo := [ 1 ]
|
||||
go add(mut foo)
|
||||
go add(mut foo)
|
||||
|
||||
for {}
|
||||
}
|
||||
|
||||
fn add(mut foo []int) {
|
||||
for {
|
||||
foo[0] = foo[0] + 1
|
||||
}
|
||||
}
|
||||
```
|
||||
|
||||
In theory, this should have two threads infinitely trying to increment `foo[0]`,
|
||||
which will eventually result in `foo[0]` getting corrupted by two threads trying to
|
||||
do the same thing at the same time (given the tight loops invovled).
|
||||
|
||||
However, I can't get this to build:
|
||||
|
||||
```
|
||||
==================
|
||||
/home/cadey/.cache/v/raceanint.tmp.c: In function ‘add_thread_wrapper’:
|
||||
/home/cadey/.cache/v/raceanint.tmp.c:1209:6: error: incompatible type for argument 1 of ‘add’
|
||||
add(arg->arg1);
|
||||
^~~
|
||||
/home/cadey/.cache/v/raceanint.tmp.c:1198:13: note: expected ‘array_int * {aka struct array *}’ but argument is of type ‘array_int {aka struct array}’
|
||||
static void add(array_int* foo);
|
||||
^~~
|
||||
/home/cadey/.cache/v/raceanint.tmp.c: In function ‘strconv__v_sprintf’:
|
||||
/home/cadey/.cache/v/raceanint.tmp.c:3611:7: warning: variable ‘th_separator’ set but not used [-Wunused-but-set-variable]
|
||||
bool th_separator = false;
|
||||
^~~~~~~~~~~~
|
||||
/home/cadey/.cache/v/raceanint.tmp.c: In function ‘print_backtrace_skipping_top_frames_linux’:
|
||||
...
|
||||
==================
|
||||
(Use `v -cg` to print the entire error message)
|
||||
|
||||
builder error:
|
||||
==================
|
||||
C error. This should never happen.
|
||||
|
||||
If you were not working with C interop, please raise an issue on GitHub:
|
||||
|
||||
https://github.com/vlang/v/issues/new/choose
|
||||
```
|
||||
|
||||
Like I said before, I also cannot file new issues about this. So if you are willing
|
||||
to help me out, please open an issue about this.
|
||||
|
||||
---
|
||||
|
||||
Overall, V looks like it is making about as much progress as I had figured it would.
|
||||
I wish the team luck in their work!
|
||||
I was in a bad mental state when I wrote this and it really shows.
|
||||
|
|
|
|||
Loading…
Reference in New Issue