[#78949] [Ruby trunk Feature#13095] [PATCH] io.c (rb_f_syscall): remove deprecation notice — kosaki.motohiro@...
Issue #13095 has been updated by Motohiro KOSAKI.
3 messages
2017/01/03
[#78997] [Ruby trunk Bug#13110] Byte-based operations for String — shugo@...
Issue #13110 has been updated by Shugo Maeda.
3 messages
2017/01/06
[#79228] Re: [ruby-cvs:64576] naruse:r57410 (trunk): Prevent GC by volatile [Bug #13150] — Eric Wong <normalperson@...>
naruse@ruby-lang.org wrote:
5 messages
2017/01/23
[#79511] Re: [ruby-cvs:64576] naruse:r57410 (trunk): Prevent GC by volatile [Bug #13150]
— Eric Wong <normalperson@...>
2017/02/13
Eric Wong <normalperson@yhbt.net> wrote:
[#79518] Re: [ruby-cvs:64576] naruse:r57410 (trunk): Prevent GC by volatile [Bug #13150]
— Nobuyoshi Nakada <nobu@...>
2017/02/13
On 2017/02/13 10:04, Eric Wong wrote:
[#79298] [Ruby trunk Bug#13085][Assigned] io.c io_fwrite creates garbage — nobu@...
Issue #13085 has been updated by Nobuyoshi Nakada.
3 messages
2017/01/29
[#79337] Re: [ruby-changes:45397] normal:r57469 (trunk): io.c: recycle garbage on write — SASADA Koichi <ko1@...>
Eric:
4 messages
2017/01/31
[#79352] Re: [ruby-changes:45397] normal:r57469 (trunk): io.c: recycle garbage on write
— Eric Wong <normalperson@...>
2017/01/31
SASADA Koichi <ko1@atdot.net> wrote:
[ruby-core:78980] [Ruby trunk Bug#13085] io.c io_fwrite creates garbage
From:
nobu@...
Date:
2017-01-05 12:58:29 UTC
List:
ruby-core #78980
Issue #13085 has been updated by Nobuyoshi Nakada.
Description updated
Another thread may make a substring of the buffer string during writing.
Then the temporarily frozen string becomes a shared root of the new substring.
Later the root gets unfrozen and modified, now the substring has an invalid pointer.
> If another thread calls String#freeze on the string we are
> currently writing; we will blindly unfreeze it during
> fwrite_unfreeze from ensure. However, I do not expect this to
> be a real-world case.
That is `test_threaded_flush` in test_io.rb,
freezing the same string simultaneously in `io_fwrite`.
----------------------------------------
Bug #13085: io.c io_fwrite creates garbage
https://bugs.ruby-lang.org/issues/13085#change-62396
* Author: Eric Wong
* Status: Open
* Priority: Normal
* Assignee:
* Target version:
* ruby -v:
* Backport: 2.2: UNKNOWN, 2.3: UNKNOWN, 2.4: UNKNOWN
----------------------------------------
Relying on rb_str_new_frozen for unconverted strings does not
save memory because copy-on-write is always triggered in
read-write I/O loops were subsequent IO#read calls will
clobber the given write buffer.
```ruby
buf = ''.b
while input.read(16384, buf)
output.write(buf)
end
```
This generates a lot of garbage starting with Ruby 2.2 (r44471).
For my use case, even `IO.copy_stream` generates garbage, since
I wrap "write" to do Digest calculation in a single pass.
I tried using rb_str_replace and reusing the string as a hidden
`(klass == 0)` thread-local, but `rb_str_replace` attempts CoW
optimization by creating new frozen objects, too:
https://80x24.org/spew/20161229004417.12304-1-e@80x24.org/raw
So, I'm not sure what to do, temporal locking seems wrong for
writing strings (I guess it's for reading?). I get
`test_threaded_flush` failures with the following:
https://80x24.org/spew/20161229005701.9712-1-e@80x24.org/raw
`IO#syswrite` has the same problem with garbage. I can use
`IO#write_nonblock` on fast filesystems while holding GVL,
I guess...
---Files--------------------------------
0001-io.c-io_fwrite-temporarily-freeze-string-when-writin.patch (2.6 KB)
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