Fix regex in benchmarks cpu/disk_on_idle (BugFix) by bladernr · Pull Request #2487 · canonical/checkbox

bladernr · 2026-04-21T13:53:27Z

Description

for disk_on_idle and cpu_on_idle, fix regex to resolve warning about invalid escape char in newer python3 versions. (older Python3 just silently passed it)
Also added CLAUDE.md to gitignore to avoid accidentally pulling in Claude instructions when making commits. Fixes Invalid escape char in benchmarks/system/disk_on_idle and cpu_on_idle #2477

Resolved issues

Resolves #2477
Resolves CHECKBOX-2238

Documentation

NA

Tests

Tested on a fresh Bionic install to verify rawstrings does work back that far:

u@bionic-tester:~$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 18.04 LTS
Release:        18.04
Codename:       bionic
u@bionic-tester:~$ python3 --version
Python 3.6.5
u@bionic-tester:~$ iostat -x -m 1 10 | python3 -c 'import sys, re; lines="".join(sys.stdin.readlines()); l=[float(n) for n in (re.findall(r"idle\n.*?(\S+)\n", lines))]; print(sum(l)/len(l),"%")'
99.787 %
u@bionic-tester:~$ iostat -x -m 1 10 | python3 -c 'import sys, re; lines="".join(sys.stdin.readlines()); l=[float(n) for n in (re.findall(r"util\n.*?(\S+)\n", lines))]; print(sum(l)/len(l),"%")'
0.013000000000000001 %

For comparison, this is Resolute where the initial warnings appeared for me, showing before and after:

bladernr@resolute-test:~$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu Resolute Raccoon (development branch)
Release:        26.04
Codename:       resolute
bladernr@resolute-test:~$ python3 --version
Python 3.14.4
bladernr@resolute-test:~$ iostat -x -m 1 10 | python3 -c 'import sys, re; lines="".join(sys.stdin.readlines()); l=[float(n) for n in (re.findall("idle\n.*?(\S+)\n", lines))]; print(sum(l)/len(l),"%")'
<string>:1: SyntaxWarning: "\S" is an invalid escape sequence. Such sequences will not work in the future. Did you mean "\\S"? A raw string is also an option.
98.978 %
bladernr@resolute-test:~$ iostat -x -m 1 10 | python3 -c 'import sys, re; lines="".join(sys.stdin.readlines()); l=[float(n) for n in (re.findall(r"idle\n.*?(\S+)\n", lines))]; print(sum(l)/len(l),"%")'
98.829 %
bladernr@resolute-test:~$ iostat -x -m 1 10 | python3 -c 'import sys, re; lines="".join(sys.stdin.readlines()); l=[float(n) for n in (re.findall("util\n.*?(\S+)\n", lines))]; print(sum(l)/len(l),"%")'
<string>:1: SyntaxWarning: "\S" is an invalid escape sequence. Such sequences will not work in the future. Did you mean "\\S"? A raw string is also an option.
0.0 %
bladernr@resolute-test:~$ iostat -x -m 1 10 | python3 -c 'import sys, re; lines="".join(sys.stdin.readlines()); l=[float(n) for n in (re.findall(r"util\n.*?(\S+)\n", lines))]; print(sum(l)/len(l),"%")'
0.0 %

* for disk_on_idle and cpu_on_idle, fix regex to resolve warning about invalid escape char in newer python3 versions. (older Python3 just silently passed it) * Also added CLAUDE.md to gitignore to avoid accidentally pulling in Claude instructions when making commits. Fixes #2477

Copilot

Pull request overview

Fixes Python SyntaxWarning noise in benchmark jobs by making the regex patterns raw strings (so \S is treated as a regex escape rather than an invalid Python string escape), and prevents accidental commits of local Claude instruction files.

Changes:

Update benchmarks/system/cpu_on_idle and benchmarks/system/disk_on_idle commands to use raw-string regex patterns in re.findall(...).
Add CLAUDE.md to .gitignore.

Reviewed changes

Copilot reviewed 1 out of 2 changed files in this pull request and generated no comments.

File	Description
`providers/base/units/benchmarks/jobs.pxu`	Uses raw-string regex literals in two benchmark job commands to eliminate invalid-escape warnings on newer Python versions.
`.gitignore`	Ignores `CLAUDE.md` to avoid committing local tooling instructions.

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codecov · 2026-04-21T13:56:53Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 58.93%. Comparing base (12822cf) to head (766b01a).
⚠️ Report is 23 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2487      +/-   ##
==========================================
+ Coverage   58.91%   58.93%   +0.01%     
==========================================
  Files         476      477       +1     
  Lines       48011    48034      +23     
  Branches     8569     8571       +2     
==========================================
+ Hits        28286    28309      +23     
+ Misses      18833    18830       -3     
- Partials      892      895       +3

Flag	Coverage Δ
provider-base	`34.19% <100.00%> (+0.08%)`	⬆️

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…pt, add unit tests, and update the job descriptions accordingly

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Pull request overview

Copilot reviewed 2 out of 4 changed files in this pull request and generated 1 comment.

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fernando79513

First of all, thanks a lot for taking the time to translate this test to Python. I think it is much clearer what the test is doing now.

I am still not sure what the purpose of running this test is. AFAIK, it's just informative.

I have a couple of concerns with the previous implementation:

The "parse_iostat_column" function only seems to work because we are choosing to parse the last value of the row. If we wanted a different column, we would have to rewrite the functionality. At this point is just a "get_idle_value" or "get_util_value"
What happens if there is more than one disk on the device? How do we know which disk to check? I tested it locally and I got something like this:

Device            r/s     rMB/s   rrqm/s  %rrqm r_await rareq-sz     w/s     wMB/s   wrqm/s  %wrqm w_await wareq-sz     d/s     dMB/s   drqm/s  %drqm d_await dareq-sz     f/s f_await  aqu-sz  %util
nvme0n1         42.76      2.47     4.08   8.71    0.12    59.09   19.88      1.41    23.14  53.79    3.09    72.61    0.00      0.00     0.00   0.00    0.00     0.00    0.72    0.35    0.07   0.79
sda              0.00      0.00     0.00   2.16    1.34    23.25    0.00      0.00     0.00  16.67    5.80     4.80    0.00      0.00     0.00   0.00    0.00     0.00    0.00    0.00    0.00   0.00
sdb              0.00      0.00     0.00  51.93    2.70    11.19    0.00      0.00     0.00   0.00    0.00     0.00    0.00      0.00     0.00   0.00    0.00     0.00    0.00    0.00    0.00   0.00

fernando79513 · 2026-05-20T14:54:50Z

+    except subprocess.CalledProcessError as e:
+        print("ERROR: iostat failed: {}".format(e), file=sys.stderr)
+        return 1


No need to try/except if you are going to raise the error anyway.

fernando79513 · 2026-05-20T14:57:34Z

+
+CLAUDE.md


There is already a CLAUDE.md file in checkbox

Suggested change

CLAUDE.md

fernando79513 · 2026-05-20T15:20:25Z

+
+
+def parse_iostat_column(output, column):
+    values = [float(n) for n in re.findall(column + r"\n.*?(\S+)\n", output)]


I know this regex was here before, but it's only working because the value you are checking is the last one of the table:

avg-cpu: %user %nice %system %iowait %steal %idle 3.62 0.00 2.46 0.08 0.00 93.84

Also, what happens if there is more than one disk?
You are getting only the value of the first disk displayed on the list:

Device r/s rMB/s rrqm/s %rrqm r_await rareq-sz w/s wMB/s wrqm/s %wrqm w_await wareq-sz d/s dMB/s drqm/s %drqm d_await dareq-sz f/s f_await aqu-sz %util sda 0.00 0.00 0.00 0.00 0.00 0.00 0.50 0.00 0.25 33.33 4.00 8.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.20 sdb 0.00 0.00 0.00 0.00 0.00 0.00 0.50 0.00 0.25 33.33 4.00 8.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.21

Is that the intended behavior?

fernando79513 · 2026-05-20T15:20:33Z

+            stderr=subprocess.PIPE,
+            universal_newlines=True,
+            check=True,
+        )


If you are analyzing the output, it's simpler to use subprocess.check_output

Suggested change

)

result = subprocess.check_output(

["iostat", "-x", "-m", "1", str(args.time)],

universal_newlines=True,

)

fernando79513 · 2026-05-20T15:21:09Z

+        print(
+            "ERROR: No '{}' values found in iostat output".format(column),
+            file=sys.stderr,
+        )
+        return 1


Just raise a system exit. Don't print and return 1.

fernando79513 · 2026-05-20T15:24:16Z

+        )
+        return 1
+    print("{:.2f}%".format(sum(values) / len(values)))
+    return 0


No need to return 0

bladernr linked an issue Apr 21, 2026 that may be closed by this pull request

Invalid escape char in benchmarks/system/disk_on_idle and cpu_on_idle #2477

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bladernr requested review from Copilot and gntzio and removed request for Copilot April 21, 2026 13:53

Copilot started reviewing on behalf of bladernr April 21, 2026 13:54 View session

bladernr changed the title ~~(BugFix) fix regex in benchmarks cpu/disk_on_idle~~ Fix regex in benchmarks cpu/disk_on_idle (BugFix) Apr 21, 2026

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Comment thread providers/base/units/benchmarks/jobs.pxu Outdated

Convert the shell command w/ embedded python into a small python scri…

10d6750

…pt, add unit tests, and update the job descriptions accordingly

bladernr requested a review from Copilot April 27, 2026 16:22

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Comment thread providers/base/tests/test_iostat_benchmark.py Outdated

update based on copilot suggestion for 3.6 compatibility

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bladernr requested a review from Copilot April 27, 2026 16:40

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bladernr added 3 commits April 27, 2026 12:47

fix black formatting

8f6f398

update to provide python 3.5 compatibility

b38d4da

fix test for 3.5

766b01a

fernando79513 self-assigned this Apr 27, 2026

bladernr requested a review from fernando79513 April 27, 2026 19:03

fernando79513 reviewed May 20, 2026

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Fix regex in benchmarks cpu/disk_on_idle (BugFix)#2487

Fix regex in benchmarks cpu/disk_on_idle (BugFix)#2487
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		def parse_iostat_column(output, column):
		values = [float(n) for n in re.findall(column + r"\n.*?(\S+)\n", output)]

-        )
+        result = subprocess.check_output(
+            ["iostat", "-x", "-m", "1", str(args.time)],
+            universal_newlines=True,
+        )

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