Re: [Tarantool-patches] [PATCH luajit] Always close profiler output file.

[Sergey Kaplun via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

Hi, Sergey!
Thanks for the patch!
Please consider my comments below.

On 10.02.25, Sergey Bronnikov wrote:
> From: Mike Pall <mike>
> 
> Reported by Guilherme Batalheiro.
> 
> (cherry picked from commit fca66335d131669cf017420af6963a7565babb58)
> 
> Before the patch, a function `prof_finish` wrote a string

Nit: s/`prof_finish`/`prof_finish()`/
Feel free to ignore.

> `No samples collected` to profiler output file and then exits.

Typo: s/profiler/a profiler/
Typo: s/exits/exited/

> Due to early exit, output file handle stay opened. This patch

Typo: s/output/the output/
Typo: s/opened/open/

> fixes condition and file handle is closed even a number of samples

Typo: s/condition/the condition/
Typo: s/file/the file/
Typo: s/even a number/even if the number/

> is equal to 0.
> 
> Sergey Bronnikov:
> * added the description and the test for the problem
> 
> Part of tarantool/tarantool#11055
> ---
> Branch: https://github.com/tarantool/luajit/tree/ligurio/gh-xxxx-close-file-profiler
> 
> Related issues:
> - https://github.com/luajIT/luajIT/issues/1304
> - https://github.com/tarantool/tarantool/issues/11055
> 
>  src/jit/p.lua                                 |  4 +--
>  ...close-profile-dump-with-0-samples.test.lua | 30 +++++++++++++++++++
>  .../script.lua                                | 14 +++++++++
>  test/tarantool-tests/utils/tools.lua          |  4 +++
>  4 files changed, 49 insertions(+), 3 deletions(-)
>  create mode 100644 test/tarantool-tests/lj-1304-close-profile-dump-with-0-samples.test.lua
>  create mode 100644 test/tarantool-tests/lj-1304-close-profile-dump-with-0-samples/script.lua
> 
> diff --git a/src/jit/p.lua b/src/jit/p.lua
> index 4569d69e..89b49584 100644
> --- a/src/jit/p.lua
> +++ b/src/jit/p.lua

<snipped>

> diff --git a/test/tarantool-tests/lj-1304-close-profile-dump-with-0-samples.test.lua b/test/tarantool-tests/lj-1304-close-profile-dump-with-0-samples.test.lua
> new file mode 100644
> index 00000000..b50b5fce
> --- /dev/null
> +++ b/test/tarantool-tests/lj-1304-close-profile-dump-with-0-samples.test.lua
> @@ -0,0 +1,30 @@
> +local tap = require('tap')
> +local test = tap.test('lj-1304-close-profile-dump-with-0-samples'):skipcond({
> +  ['Test requires /proc filesystem'] = jit.os == 'OSX',

I suppose we may get off this skipcond, see the last comment.

> +})
> +local utils = require('utils')
> +
> +test:plan(1)
> +
> +-- Test file to demonstrate LuaJIT incorrect behaviour with missed
> +-- close a file handle for profile output file.

Typo? s/close/closing/
Typo: s/profile/the profile/

> +-- See also: https://github.com/luajIT/luajIT/issues/1304
> +
> +local p_filename = '/tmp/profile'

It's better to use for the profile name generation the following
function:
| local profilename = require("utils").tools.profilename

> +
> +-- <makecmd> runs %testname%/script.lua by <LUAJIT_TEST_BINARY>
> +-- with the given environment, launch options and CLI arguments.
> +local script = utils.exec.makecmd(arg)

I don't get it. Why do we need the separate script for it?

> +-- Execute a Lua script with start and stop LuaJIT profiler,
> +-- it is expected no samples found by profiler. The script's
> +-- output is suppressed, it is not interested.
> +local _ = script(p_filename)
> +
> +local p_content = io.open(p_filename):read('a*')
> +test:is(utils.tools.trim(p_content), '[No samples collected]',
> +        'profile dump has no samples')

Minor: I suppose simple `test:like()` will be enough. In that case there
is no need to use the newly introduced `trim()` function here.

> +
> +-- Teardown.
> +os.remove(p_filename)
> +
> +test:done(true)
> diff --git a/test/tarantool-tests/lj-1304-close-profile-dump-with-0-samples/script.lua b/test/tarantool-tests/lj-1304-close-profile-dump-with-0-samples/script.lua
> new file mode 100644
> index 00000000..77335a08
> --- /dev/null
> +++ b/test/tarantool-tests/lj-1304-close-profile-dump-with-0-samples/script.lua
> @@ -0,0 +1,14 @@
> +local p_options = 'ri1'

It is better to use a much bigger interval (`i99999` for example) to be
sure that there will be no samples collected. Also, the `r` option isn't
required.

> +local p_filename = assert(arg[1], 'filename argument is missing')
> +
> +require('jit.p').start(p_options, p_filename)
> +
> +-- No code to generate profiling samples.
> +
> +-- Stop profiler to execute `jit/p.lua:prof_fmt()`. With zero
> +-- samples it triggers early return without closing the file.
> +require('jit.p').stop()

I suppose we may require this module only once.

> +
> +-- Make sure LuaJIT profiler is close a file handle.
> +local ls_output = io.popen('ls -l /proc/$$/fd'):read('a*')

Minor: I am not sure that we really need this check. The descriptor will
be closed when it will be garbage collected, IINM, so there is no leak,
actually. I suggest dropping it and checking only the content of the
file -- this is the main issue regarding `jit.p` solved by that commit.

Also, in this case we can run this test on OSX.

> +assert(ls_output:find(p_filename) == nil, 'file is open')
> diff --git a/test/tarantool-tests/utils/tools.lua b/test/tarantool-tests/utils/tools.lua
> index 33fcae78..9cb65daf 100644
> --- a/test/tarantool-tests/utils/tools.lua
> +++ b/test/tarantool-tests/utils/tools.lua
> @@ -21,4 +21,8 @@ function M.read_file(path)
>    return content
>  end
>  
> +function M.trim(str)
> +  return (str:gsub('^%s*(.-)%s*$', '%1'))
> +end
> +
>  return M
> -- 
> 2.34.1
> 

-- 
Best regards,
Sergey Kaplun