Hello, Sergey,

thanks for review! Please see my comments.

Updated version was force-pushed to the branch.

Sergey

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/

Fixed:

@@ -7,10 +7,10 @@ local utils = require('utils')
 test:plan(1)
 
 -- Test file to demonstrate LuaJIT incorrect behaviour with missed
--- close a file handle for profile output file.
+-- closing a file handle for the profile output file.
 -- See also: https://github.com/luajIT/luajIT/issues/1304
 
-local p_filename = '/tmp/profile'
+local p_filename = utils.tools.profilename
 
 -- <makecmd> runs %testname%/script.lua by <LUAJIT_TEST_BINARY>
 -- with the given environment, launch options and CLI arguments.

+-- 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

Fixed:

+
+-- <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?

prof_finish() is executed first time on calling `jit.p.stop()`

and executed second time when GC finalizer is calling [1] and therefore message "'[No samples collected]'" appears

two times in the output file.

1. https://github.com/tarantool/luajit/blob/80360fb2e570ce8d54ff59ccf0bcd5dfb6b98527/src/jit/p.lua#L290

We can inline script.lua to a test body and call garbage collector manually,

but I propose to leave it as is because  executing as a separate process is more real use case.

+-- 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.

The check checks that exactly one "[No samples collected]" is in a file.

Before the patch, a file contains two "[No samples collected]".

+
+-- 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.

Fixed:

--- 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
@@ -1,6 +1,8 @@
 local jit_p = require('jit.p')
 
-local p_options = 'ri1'
+-- Using a bigger interval to make sure that there will be no
+-- samples collected.
+local p_options = 'i99999'
 local p_filename = assert(arg[1], 'filename argument is missing')
 
 jit_p.start(p_options, p_filename)

+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.

Fixed:

--- 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
@@ -1,13 +1,15 @@
+local jit_p = require('jit.p')
+
 local p_options = 'ri1'
 local p_filename = assert(arg[1], 'filename argument is missing')
 
-require('jit.p').start(p_options, p_filename)
+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()
+jit_p.stop()
 
 -- Make sure LuaJIT profiler is close a file handle.
 local ls_output = io.popen('ls -l /proc/$$/fd'):read('a*')

+
+-- 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.

This is for checking that `prof_finish` behaves correctly.

fd leak is a resource leak and there is a separate CWE for this -

https://cwe.mitre.org/data/definitions/775.html

On my machine max number of file descriptors is 126693 per process:

[0] ~ $ ulimit -n
126693

You will get file descriptor exhaustion if you will run

`require('jit.p').start()` 126693 times with different output files.

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