Fix sonic-utilities submodule update failure due to ijson library

[venkit-nexthop]

What I did

Forced the use of python backend for the ijson library

How I did it

- import ijson
+ import ijson.backends.python as ijson

How to verify it

Run the CI process of running sonic-mgmt test in a KVM environment.

Previous command output (if the output of a command-line utility has changed)

New command output (if the output of a command-line utility has changed)

[mssonicbld]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[mssonicbld]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[venkit-nexthop]

@saiarcot895 @deepak-singhal0408 @prsunny

I made a fix recommended by @saiarcot895. But code coverage is failing due to lack of coverage in the following lines:

try:
import ijson.backends.yajl2 as ijson
except ImportError: <--------------------------------------
import ijson.backends.python as ijson <------------------

I am not sure if it is worth adding coverage for this. I am not sure how to add coverage for imports.
Is there a way to override the coverage check?

Alternatively, I can simply add the python backend.

[mssonicbld]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[venkit-nexthop]

@saiarcot895 @deepak-singhal0408
I decided to simply use the python backend due to the test coverage issue I described earlier. The primary issue the earlier PR was solving was to save on memory and this change satisfies that objective equally. Although it was slightly slower than the C backend, the performance was not too bad.
Please approve this PR.

[saiarcot895]

@venkit-nexthop Looks like this method doesn't actually work:

2026 Feb 19 09:02:20.452788 vlab-03 WARNING monit[872]: 'routeCheck' status failed (1) -- Traceback (most recent call last):#012  File "/usr/local/bin/route_check.py", line 40, in <module>#012    import ijson.backends.python as ijson#012  File "/usr/local/lib/python3.13/dist-packages/ijson/__init__.py", line 36, in <module>#012    backend = _default_backend()#012  File "/usr/local/lib/python3.13/dist-packages/ijson/__init__.py", line 32, in _default_backend#012    return get_backend(backend)#012  File "/usr/local/lib/python3.13/dist-packages/ijson/__init__.py", line 24, in get_backend#012    return importlib.import_module('ijson.backends.' + backend)#012           ~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^#012  File "/usr/lib/python3.13/importlib/__init__.py", line 88, in import_module#012    return _bootstrap._gcd_import(name[level:], package, level)#012           ~~~

The _default_backend function in the __init__.py for the ijson module is still being run, I guess because it needs to be imported before ijson.backend.python can be imported.

I'm thinking setting the IJSON_BACKEND environment variable for monit is the next best method?

[venkit-nexthop]

@venkit-nexthop Looks like this method doesn't actually work:

2026 Feb 19 09:02:20.452788 vlab-03 WARNING monit[872]: 'routeCheck' status failed (1) -- Traceback (most recent call last):#012  File "/usr/local/bin/route_check.py", line 40, in <module>#012    import ijson.backends.python as ijson#012  File "/usr/local/lib/python3.13/dist-packages/ijson/__init__.py", line 36, in <module>#012    backend = _default_backend()#012  File "/usr/local/lib/python3.13/dist-packages/ijson/__init__.py", line 32, in _default_backend#012    return get_backend(backend)#012  File "/usr/local/lib/python3.13/dist-packages/ijson/__init__.py", line 24, in get_backend#012    return importlib.import_module('ijson.backends.' + backend)#012           ~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^#012  File "/usr/lib/python3.13/importlib/__init__.py", line 88, in import_module#012    return _bootstrap._gcd_import(name[level:], package, level)#012           ~~~

The _default_backend function in the __init__.py for the ijson module is still being run, I guess because it needs to be imported before ijson.backend.python can be imported.

I'm thinking setting the IJSON_BACKEND environment variable for monit is the next best method?

I had an earlier version of this PR where I was not using ijson and instead had my own parsing logic.
@deepak-singhal0408 recommended using ijson instead. I am now wondering if I should go back to that code.
@deepak-singhal0408 @saiarcot895 please let me know what you think here.

[deepak-singhal0408]

@venkit-nexthop Looks like this method doesn't actually work:

2026 Feb 19 09:02:20.452788 vlab-03 WARNING monit[872]: 'routeCheck' status failed (1) -- Traceback (most recent call last):#012  File "/usr/local/bin/route_check.py", line 40, in <module>#012    import ijson.backends.python as ijson#012  File "/usr/local/lib/python3.13/dist-packages/ijson/__init__.py", line 36, in <module>#012    backend = _default_backend()#012  File "/usr/local/lib/python3.13/dist-packages/ijson/__init__.py", line 32, in _default_backend#012    return get_backend(backend)#012  File "/usr/local/lib/python3.13/dist-packages/ijson/__init__.py", line 24, in get_backend#012    return importlib.import_module('ijson.backends.' + backend)#012           ~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^#012  File "/usr/lib/python3.13/importlib/__init__.py", line 88, in import_module#012    return _bootstrap._gcd_import(name[level:], package, level)#012           ~~~

The _default_backend function in the __init__.py for the ijson module is still being run, I guess because it needs to be imported before ijson.backend.python can be imported.
I'm thinking setting the IJSON_BACKEND environment variable for monit is the next best method?

I had an earlier version of this PR where I was not using ijson and instead had my own parsing logic. @deepak-singhal0408 recommended using ijson instead. I am now wondering if I should go back to that code. @deepak-singhal0408 @saiarcot895 please let me know what you think here.

Hi @venkit-nexthop, @saiarcot895
i suggest setting this env variable before importing ijson in the route_check script itself..
Lets not go back to custom parser code..

os.environ.setdefault('IJSON_BACKEND', 'python')
import ijson

this is the official recommendation from ijson documenation as well..

https://github.com/ICRAR/ijson#backends
relevant content:

Importing the top level library as import ijson uses the first available backend in the same order of the list above, and its name is recorded under ijson.backend. If the IJSON_BACKEND environment variable is set its value takes precedence and is used to select the default backend.

[venkit-nexthop]

Sounds good @deepak-singhal0408 I will try setting env variable before importing in the route_check script.