-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
https://reviews.apache.org/r/52559/
-----------------------------------------------------------
(Updated Oct. 10, 2016, 12:16 a.m.)
Review request for hive, Sergey Shelukhin, Thejas Nair, Vaibhav Gumashta, and
Yongzhi Chen.
Changes
-------
optimized the locking
Bugs: HIVE-14799
https://issues.apache.org/jira/browse/HIVE-14799
Repository: hive-git
Description
-------
This patch is going to fix a couple of Driver issues related to the close
request from a thread other than the one running the query (e.g. from
SQLOperation cancel via Timeout or Ctrl-C):
1. Driver is not thread safe and usually supports only one thread at time since
it has variables like ctx, plan which are not thread protected. But certain
special use cases need access the Driver objects from multiply threads. For
example, when a query runs in a background thread, driver.close is invoked in
another thread by the query timeout (see HIVE-4924). The close process could
nullify the shared variables like ctx which could cause NPE in the other query
thread which is using them. This runtime exception is unpredictable and not
well handled in the code. Some resources (e.g. locks, files) are left behind
and not be cleaned because there are no more available = references to them. In
this patch, I use the waiting in the close which makes sure only one thread
uses these variables and the resource cleaning happens after the query finished
(or interrupted).
2. SQLOperation.cancel sends the interrupt signal to the background thread
running the query (via backgroundHandle.cancel(true)) but it could not stop
that process since there is no code to capture the signal in the process. In
another word, current timeout code could not gracefully and promptly stop the
query process, though it could eventually stop the process by killing the
running tasks (e.g. MapRedTask) via driverContext.shutdown (see HIVE-5901). So
in the patch, I added a couple of checkpoints to intercept the interrupt signal
either set by close method (a volatile variable) or thread.interrupt. They
should be helpful to capture these signals earlier , though not intermediately.
Diffs (updated)
-----
ql/src/java/org/apache/hadoop/hive/ql/Driver.java dd55434
Diff: https://reviews.apache.org/r/52559/diff/
Testing
-------
Manually tests
Precommit tests
Thanks,
Chaoyu Tang
