Invalid default value for timeout in PollingFuture

[TMo484]

There is a bug in the initialization of timeout inside the PollingFuture class, where the default value passed into various methods is of type object when it is expected to be an int, float, or None.

• Link to _DEFAULT_VALUE instantiation inside the PollingFuture class
• Downstream methods that expect type int (or None, based on traceback): PollingFuture.result and PollingFuture.exception

The below example uses the bigquery client to generate and execute an Operation, and then demonstrates the raised error when attempting to access the .exception method.

Environment Details
Windows 10
Python 3.9.5
pip 21.1.1
pip packages:
google-cloud-bigquery==3.11.4
google-api-core==2.11.1

Steps to reproduce

1. python -m venv google_api_test
2. google_api_test\scripts\pip install google-cloud-bigquery google-api-core

Code Example

from google.cloud import bigquery
client = bigquery.client.Client()

job = client.query(
        """
        SELECT
          CONCAT(
            'https://stackoverflow.com/questions/',
            CAST(id as STRING)) as url,
          view_count
        FROM `bigquery-public-data.stackoverflow.posts_questions`
        WHERE tags like '%google-bigquery%'
        ORDER BY RAND() DESC"""
    )

job.exception()

Stack Trace

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "{WINDOWS_ROOT}\google_api_test\lib\site-packages\google\api_core\future\polling.py", line 282, in exception
    self._blocking_poll(timeout=timeout)
  File "{WINDOWS_ROOT}\google_api_test\lib\site-packages\google\cloud\bigquery\job\query.py", line 1257, in _blocking_poll
    super(QueryJob, self)._blocking_poll(timeout=timeout, **kwargs)
  File "{WINDOWS_ROOT}\google_api_test\lib\site-packages\google\api_core\future\polling.py", line 137, in _blocking_poll
    polling(self._done_or_raise)(retry=retry)
  File "{WINDOWS_ROOT}\google_api_test\lib\site-packages\google\api_core\retry.py", line 349, in retry_wrapped_func
    return retry_target(
  File "{WINDOWS_ROOT}\google_api_test\lib\site-packages\google\api_core\retry.py", line 191, in retry_target
    return target()
  File "{WINDOWS_ROOT}\google_api_test\lib\site-packages\google\cloud\bigquery\job\query.py", line 1379, in _done_or_raise
    self._reload_query_results(retry=retry, timeout=transport_timeout)
  File "{WINDOWS_ROOT}\google_api_test\lib\site-packages\google\cloud\bigquery\job\query.py", line 1360, in _reload_query_results
    self._query_results = self._client._get_query_results(
  File "{WINDOWS_ROOT}\google_api_test\lib\site-packages\google\cloud\bigquery\client.py", line 1898, in _get_query_results
    timeout = max(timeout, _MIN_GET_QUERY_RESULTS_TIMEOUT)
TypeError: '>' not supported between instances of 'int' and 'object'

Side Note:
This example does not directly demonstrate the error effect on the job.result() function as, in this example through BigQuery, the PollingFuture.result method is wrapped in QueryJob.result (link to class). This wrapper overrides the invalid timeout with an acceptable timeout value of None (link to argument)

[vchudnov-g]

Thanks for reporting this and suggesting a fix (TMo484#1). We will review this as soon as can.