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https://issues.apache.org/jira/browse/IMPALA-14872?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Michael Smith updated IMPALA-14872:
-----------------------------------
Description:
{{query_driver_map_}} is a highly contended data structure. Accessing it
acquires a lock that prevents any other query progress on queries that share a
shard, and by default there are only 4 shards.
{{GetMaxBackendStateLagMs}} acquires a lock on each {{BackendState}} object,
which may also be in use (notably while sending a
{{CancelQueryFInstancesRequestPB}} RPC in Cancel()), for a coordinator within
{{DoFuncForAllEntries}} in
https://github.com/apache/impala/blob/4.5.0/be/src/service/impala-server.cc#L2983.
Let's stop doing that.
was:
query_driver_map_ is a highly contended data structure. Accessing it acquires a
lock that prevents any other query progress on queries that share a shard, and
by default there are only 4 shards.
GetMaxBackendStateLagMs acquires a lock on each BackendState object, which may
also be in use (notably while sending a CancelQueryFInstancesRequestPB RPC in
Cancel()), for a coordinator within DoFuncForAllEntries in
https://github.com/apache/impala/blob/4.5.0/be/src/service/impala-server.cc#L2983.
Let's stop doing that.
> Don't hold query_driver_map_ lock while calling GetMaxBackendStateLagMs
> -----------------------------------------------------------------------
>
> Key: IMPALA-14872
> URL: https://issues.apache.org/jira/browse/IMPALA-14872
> Project: IMPALA
> Issue Type: Bug
> Affects Versions: Impala 4.5.0
> Reporter: Michael Smith
> Priority: Major
>
> {{query_driver_map_}} is a highly contended data structure. Accessing it
> acquires a lock that prevents any other query progress on queries that share
> a shard, and by default there are only 4 shards.
> {{GetMaxBackendStateLagMs}} acquires a lock on each {{BackendState}} object,
> which may also be in use (notably while sending a
> {{CancelQueryFInstancesRequestPB}} RPC in Cancel()), for a coordinator within
> {{DoFuncForAllEntries}} in
> https://github.com/apache/impala/blob/4.5.0/be/src/service/impala-server.cc#L2983.
> Let's stop doing that.
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