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https://issues.apache.org/jira/browse/HDFS-11436?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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James Clampffer updated HDFS-11436:
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Attachment: HDFS-11436.HDFS-8707.000.patch
Patch to keep the promise alive and avoid the race condition.
> libhdfs++: Fix race condition in ScopedResolver
> -----------------------------------------------
>
> Key: HDFS-11436
> URL: https://issues.apache.org/jira/browse/HDFS-11436
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: hdfs-client
> Reporter: James Clampffer
> Assignee: James Clampffer
> Attachments: HDFS-11436.HDFS-8707.000.patch
>
>
> ScopedResolver holds a shared_ptr to a std::promise to do async stuff while
> the calling thread blocks. The spec allows promise::set_value to unblock
> future::wait immediately which causes future::get_value to race to read
> whatever the promise contains before the state and value owned by the promise
> is destroyed. In this case even though the ScopedResolver holds a shared_ptr
> to the promise which looks like it'd prevent this but it's possible for wait
> to unblock fast enough for the destructor on ScopedResolver to be called
> which ends up destroying the promise. GCC's implementation tends of promises
> and futures will hit this and will show up in valgrind as a bunch of invalid
> reads if the timings are right to set up the race.
> Simple fix right now is make sure the callback captures a shared_ptr to the
> promise. Longer term fix may be to make a class that encapsulates the
> promise and future with a reference counting mechanism to prevent more of
> these bugs and use that instead of the std lib versions.
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