[PATCH 2/2] tools/perf: Fix parallel-perf python script to replace new python syntax ":=" usage

[Athira Rajeev]

> On 16 Jun 2024, at 8:33 PM, Adrian Hunter <adrian.hunter at intel.com> wrote:
> 
> On 14/06/24 20:27, Athira Rajeev wrote:
>> perf test "perf script tests" fails as below in systems
>> with python 3.6
>> 
>> File "/home/athira/linux/tools/perf/tests/shell/../../scripts/python/parallel-perf.py", line 442
>> if line := p.stdout.readline():
>>             ^
>> SyntaxError: invalid syntax
>> --- Cleaning up ---
>> ---- end(-1) ----
>> 92: perf script tests: FAILED!
>> 
>> This happens because ":=" is a new syntax that assigns values
>> to variables as part of a larger expression. This is introduced
>> from python 3.8 and hence fails in setup with python 3.6
> 
> According to below python 3.6 is end-of-life
> 
> https://devguide.python.org/versions/
> 
> What was still using python 3.6?
> 
>> Address this by splitting the large expression and check the
>> value in two steps:
>> Previous line: if line := p.stdout.readline():
>> Current change:
>> line = p.stdout.readline()
>> if line:
>> 
>> With patch
>> 
>> ./perf test "perf script tests"
>>  93: perf script tests:  Ok
>> 
>> Signed-off-by: Athira Rajeev <atrajeev at linux.vnet.ibm.com>
> 
> Acked-by: Adrian Hunter <adrian.hunter at intel.com>

Observed this on SLES 15 SP5
Thanks for the Acked-by Adrian

I will be posting a V2 adding this Acked-by for this Patch 2 and addressing changes suggested in handling "/tmp/perf-%d.map” files in Patch 1

Thanks
Athira
> 
>> ---
>> tools/perf/scripts/python/parallel-perf.py | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>> 
>> diff --git a/tools/perf/scripts/python/parallel-perf.py b/tools/perf/scripts/python/parallel-perf.py
>> index 21f32ec5ed46..be85fd7f6632 100755
>> --- a/tools/perf/scripts/python/parallel-perf.py
>> +++ b/tools/perf/scripts/python/parallel-perf.py
>> @@ -439,7 +439,8 @@ def ProcessCommandOutputLines(cmd, per_cpu, fn, *x):
>> pat = re.compile(r"\s*\[[0-9]+\]")
>> p = subprocess.Popen(cmd, stdout=subprocess.PIPE)
>> while True:
>> - if line := p.stdout.readline():
>> + line = p.stdout.readline()
>> + if line:
>> line = line.decode("utf-8")
>> if pat.match(line):
>> line = line.split()