[Pkg-matrix-maintainers] Bug#1105140: matrix-synapse:FTBFS:build failed(WorkerLockTest Timeout on riscv64)

[Yue Gui]

Source: matrix-synapse
Version: 1.128.0-1
Severity: serious
Tags: FTBFS, patch
User: debian-riscv at lists.debian.org
Usertags: riscv64

Dear matrix-synapse maintainer,
The package matrix-synapse build failed on riscv64.The crucial buildd log
below:
```

=================================== FAILURES ===================================
___________________ WorkerLockTestCase.test_lock_contention ____________________

self = <tests.handlers.test_worker_lock.WorkerLockTestCase
testMethod=test_lock_contention>

    def test_lock_contention(self) -> None:
        """Test lock contention when a lot of locks wait on a single worker"""

        # It takes around 0.5s on a 5+ years old laptop
        with test_timeout(5):
            nb_locks = 500
            d = self._take_locks(nb_locks)
>           self.assertEqual(self.get_success(d), nb_locks)

/build/reproducible-path/matrix-synapse-1.128.0/.pybuild/cpython3_3.13_matrix-synapse/build/tests/handlers/test_worker_lock.py:61:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
/build/reproducible-path/matrix-synapse-1.128.0/.pybuild/cpython3_3.13_matrix-synapse/build/tests/unittest.py:692:
in get_success
    self.pump(by=by)
/build/reproducible-path/matrix-synapse-1.128.0/.pybuild/cpython3_3.13_matrix-synapse/build/tests/unittest.py:688:
in pump
    self.reactor.pump([by] * 100)
/usr/lib/python3/dist-packages/twisted/internet/task.py:838: in pump
    self.advance(amount)
/build/reproducible-path/matrix-synapse-1.128.0/.pybuild/cpython3_3.13_matrix-synapse/build/tests/server.py:642:
in advance
    super().advance(0)
/usr/lib/python3/dist-packages/twisted/internet/task.py:830: in advance
    call.func(*call.args, **call.kw)
/build/reproducible-path/matrix-synapse-1.128.0/.pybuild/cpython3_3.13_matrix-synapse/build/synapse/util/__init__.py:201:
in wrapped_callback
    callback(*args, **kwargs)
/build/reproducible-path/matrix-synapse-1.128.0/.pybuild/cpython3_3.13_matrix-synapse/build/synapse/handlers/worker_lock.py:191:
in _wake_all_locks
    if not deferred.called:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

self = <tests.utils.test_timeout object at 0x3f9e3e74d0>, signum = 14
frame = <frame at 0x3f9bda9560, file
'/build/reproducible-path/matrix-synapse-1.128.0/.pybuild/cpython3_3.13_matrix-synapse/build/synapse/handlers/worker_lock.py',
line 191, code _wake_all_locks>

    def handle_timeout(self, signum: int, frame: Optional[FrameType]) -> None:
>       raise TestTimeout(self.error_message)
E       tests.utils.TestTimeout: Test timed out after 5s

/build/reproducible-path/matrix-synapse-1.128.0/.pybuild/cpython3_3.13_matrix-synapse/build/tests/utils.py:424:
TestTimeout

```
The full buildd log is here:
https://buildd.debian.org/status/fetch.php?pkg=matrix-synapse&arch=riscv64&ver=1.128.0-1&stamp=1746950558&raw=0

My solution to this issue:
The `test_lock_contention` test, which simulates high lock contention, is
timing out on RISC-V systems likely due to inherent performance differences
of the architecture compared to more established platforms like x86_64, for
which the current 5-second timeout is calibrated.

To address this without masking potential regressions on other
architectures, I propose to conditionally adjust the timeout duration for
the RISC-V architecture. This is achieved by detecting the architecture
using `platform.machine()` within the test case and applying a more lenient
timeout (e.g., 15 seconds)  specifically for RISC-V.The debdiff patch is in
the attachment.I have tested that locally,and it works well.Please let me
know whether this solution can be accepted.

Gui-Yue
Best Regards
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