Details
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Bug
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Status: Resolved
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Major
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Resolution: Fixed
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Impala 2.1
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None
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None
Description
The scanner thread registers with the token mgr in Prepare() (Execute from the client) and doesn't issue work to the io_mgr until GetNext() (Fetch from the client). After registering with the token mgr, the token mgr will offer tokens (HdfsScanNode::ThreadAvailableCb) which spins up scanner threads. Since there are no ranges issued, the scanner threads busy spin keeping a core busy per thread.
This is bad anytime there is a large gap between Prepare/Open() and GetNext(). This can happen because the client went away (spinning until query timeout) or other parts of the plan take a long time (i.e. processing the build side of a join).
Attachments
Attachments
Issue Links
- is duplicated by
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IMPALA-2901 Impala query using 100% CPU system state
- Resolved