[SPARK-29046][SQL][2.4] Fix NPE in SQLConf.get when active SparkContext is stopping #25798
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… stopping ### What changes were proposed in this pull request? This patch fixes the bug regarding NPE in SQLConf.get, which is only possible when SparkContext._dagScheduler is null due to stopping SparkContext. The logic doesn't seem to consider active SparkContext could be in progress of stopping. Note that it can't be encountered easily as SparkContext.stop() blocks the main thread, but there're many cases which SQLConf.get is accessed concurrently while SparkContext.stop() is executing - users run another threads, or listener is accessing SQLConf.get after dagScheduler is set to null (this is the case what I encountered.) ### Why are the changes needed? The bug brings NPE. ### Does this PR introduce any user-facing change? No ### How was this patch tested? Previous patch apache#25753 was tested with new UT, and due to disruption with other tests in concurrent test run, the test is excluded in this patch. Closes apache#25790 from HeartSaVioR/SPARK-29046-v2. Authored-by: Jungtaek Lim (HeartSaVioR) <[email protected]> Signed-off-by: Dongjoon Hyun <[email protected]>
srowen
approved these changes
Sep 16, 2019
kiszk
approved these changes
Sep 16, 2019
HyukjinKwon
approved these changes
Sep 16, 2019
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Looks like CI build doesn't have been triggered recently. |
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Thank you for making a backporting, too. |
dongjoon-hyun
approved these changes
Sep 16, 2019
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Test build #4865 has started for PR 25798 at commit |
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Test build #110635 has finished for PR 25798 at commit
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Thank you all. Merged to branch-2.4. |
dongjoon-hyun
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Sep 17, 2019
…xt is stopping ### What changes were proposed in this pull request? This patch fixes the bug regarding NPE in SQLConf.get, which is only possible when SparkContext._dagScheduler is null due to stopping SparkContext. The logic doesn't seem to consider active SparkContext could be in progress of stopping. Note that it can't be encountered easily as SparkContext.stop() blocks the main thread, but there're many cases which SQLConf.get is accessed concurrently while SparkContext.stop() is executing - users run another threads, or listener is accessing SQLConf.get after dagScheduler is set to null (this is the case what I encountered.) ### Why are the changes needed? The bug brings NPE. ### Does this PR introduce any user-facing change? No ### How was this patch tested? Previous patch #25753 was tested with new UT, and due to disruption with other tests in concurrent test run, the test is excluded in this patch. Closes #25798 from HeartSaVioR/SPARK-29046-branch-2.4. Authored-by: Jungtaek Lim (HeartSaVioR) <[email protected]> Signed-off-by: Dongjoon Hyun <[email protected]>
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What changes were proposed in this pull request?
This patch fixes the bug regarding NPE in SQLConf.get, which is only possible when SparkContext._dagScheduler is null due to stopping SparkContext. The logic doesn't seem to consider active SparkContext could be in progress of stopping.
Note that it can't be encountered easily as SparkContext.stop() blocks the main thread, but there're many cases which SQLConf.get is accessed concurrently while SparkContext.stop() is executing - users run another threads, or listener is accessing SQLConf.get after dagScheduler is set to null (this is the case what I encountered.)
Why are the changes needed?
The bug brings NPE.
Does this PR introduce any user-facing change?
No
How was this patch tested?
Previous patch #25753 was tested with new UT, and due to disruption with other tests in concurrent test run, the test is excluded in this patch.