Flaky test: TestGPUUpdaters::test_external_memory

[trivialfis]

https://xgboost-ci.net/blue/organizations/jenkins/xgboost/detail/PR-6258/4/pipeline/207

[2020-10-28T10:53:16.632Z] tests/python-gpu/test_gpu_updaters.py::TestGPUUpdaters::test_gpu_hist_device_dmatrix PASSED
[2020-10-28T10:53:56.001Z] tests/python-gpu/test_gpu_updaters.py::TestGPUUpdaters::test_external_memory double free or corruption (fasttop)
[2020-10-28T10:53:56.001Z] Fatal Python error: Segmentation fault
[2020-10-28T10:53:56.001Z] 
[2020-10-28T10:53:56.001Z] Thread 0x00007f3f329ba700 (most recent call first):
[2020-10-28T10:53:56.001Z]   File "/opt/python/Fatal Python error: Aborted
[2020-10-28T10:53:56.001Z] 
[2020-10-28T10:53:56.001Z] tests/ci_build/test_python.sh: line 42:  4497 Aborted                 (core dumped) pytest -v -s -rxXs --fulltrace --durations=0 -m "not mgpu" ${args} tests/python-gpu

https://xgboost-ci.net/blue/organizations/jenkins/xgboost/detail/PR-6302/3/pipeline

[2020-10-28T10:52:27.516Z]         ret : int
[2020-10-28T10:52:27.516Z]             return value from API calls
[2020-10-28T10:52:27.516Z]         """
[2020-10-28T10:52:27.516Z]         if ret != 0:
[2020-10-28T10:52:27.516Z] >           raise XGBoostError(py_str(_LIB.XGBGetLastError()))
[2020-10-28T10:52:27.516Z] E           xgboost.core.XGBoostError: std::bad_alloc
[2020-10-28T10:52:27.516Z] 

[2020-10-28T10:52:27.516Z] /home/ubuntu/.local/lib/python3.7/site-packages/xgboost/core.py:186: XGBoostError

[2020-10-28T10:52:27.516Z] ---------------------------------- Hypothesis ----------------------------------
[2020-10-28T10:52:27.516Z] Falsifying example: test_external_memory(
[2020-10-28T10:52:27.516Z]     self=<test_gpu_updaters.TestGPUUpdaters at 0x7ff94cf55050>,
[2020-10-28T10:52:27.516Z]     param={'colsample_bylevel': 0.5,
[2020-10-28T10:52:27.516Z]      'colsample_bytree': 0.5,
[2020-10-28T10:52:27.516Z]      'grow_policy': 'lossguide',
[2020-10-28T10:52:27.516Z]      'max_bin': 2,
[2020-10-28T10:52:27.516Z]      'max_depth': 0,
[2020-10-28T10:52:27.516Z]      'max_leaves': 1,
[2020-10-28T10:52:27.516Z]      'min_child_weight': 0.5,
[2020-10-28T10:52:27.516Z]      'seed': 0,
[2020-10-28T10:52:27.516Z]      'single_precision_histogram': True},
[2020-10-28T10:52:27.516Z]     num_rounds=1,
[2020-10-28T10:52:27.516Z]     dataset=boston,
[2020-10-28T10:52:27.516Z] )

[trivialfis]

https://xgboost-ci.net/blue/organizations/jenkins/xgboost/detail/PR-6187/15/pipeline

[trivialfis]

Seems to be resolved by reopening the PR. Before reopening it's deterministically failing. Not sure why. Closing again and will investigate once there's something more concrete.

[trivialfis]

https://xgboost-ci.net/blue/organizations/jenkins/xgboost/detail/PR-6379/2/pipeline