Scenario Risk QA test failure on 32-bit machine (CI)

[Lars Butler]

This error:
http://ci.openquake.org/job/oq-engine/487/testReport/junit/qa_tests.scenario_risk_unittest/ScenarioRiskQATest/test_scenario_risk_sample_based/

Failed

qa_tests.scenario_risk_unittest.ScenarioRiskQATest.test_scenario_risk_sample_based (from nosetests)

Failing for the past 1 build (Since #487 )
Took 11 min.
add description
Error Message

193.949563098 != 193.233919602 within 4 places
TRACE: ROOT -> 0 -> 'mean'
Stacktrace

Traceback (most recent call last):
  File "/usr/lib/python2.7/unittest/case.py", line 327, in run
    testMethod()
  File "/var/lib/jenkins/jobs/oq-engine/workspace/qa_tests/scenario_risk_unittest.py", line 191, in test_scenario_risk_sample_based
    self._verify_loss_map(expected_loss_map_file, expected_loss_map)
  File "/var/lib/jenkins/jobs/oq-engine/workspace/qa_tests/scenario_risk_unittest.py", line 63, in _verify_loss_map
    self, expected_data, actual_lm_data, places=self.LOSSMAP_PRECISION)
  File "/var/lib/jenkins/jobs/oq-engine/workspace/tests/utils/helpers.py", line 337, in assertDeepAlmostEqual
    raise exc
AssertionError: 193.949563098 != 193.233919602 within 4 places
TRACE: ROOT -> 0 -> 'mean'

[Lars Butler (lars-butler)]

The problem is that the epsilon random seed parameter was being passed to Random.seed() as a string (instead of being cast as an int first). Since our CI server runs on a 32-bit machine, the hash value of the seed was different than 64-bit machines running the same code. The solution was a one-line: cast the seed to an int.

This does not completely solve the issue, however, but as long as values are chosen from the interval [-2147483648, 2147483647] (a 32-bit singed int), the random sampling done in the scenario risk calculator will behave the same on 64-bit and 32-bit machines.

[Lars Butler (lars-butler)]

Pull request: https://github.com/gem/oq-engine/pull/739