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Posted to issues-all@impala.apache.org by "Quanlong Huang (Jira)" <ji...@apache.org> on 2022/09/06 12:56:00 UTC
[jira] [Updated] (IMPALA-11409) Skip UpdateCatalogMetrics if another thead is on-going in it
[ https://issues.apache.org/jira/browse/IMPALA-11409?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Quanlong Huang updated IMPALA-11409:
------------------------------------
Description:
Impala coordinator tracks local metrics of the catalog, e.g. number of dbs/tables. When use_local_catalog is enabled, it also tracks the cache metrics, e.g. cache hit/miss count/rate.
These metrics are updated at the end of each statement, even for simple statements like "USE <db>", "SET var=xxx", "SELECT 1". The catalog update thread will also update the metrics in the end.
[https://github.com/apache/impala/blob/bb610dee09a8069bb993b4c668f7e481c1774b70/be/src/service/impala-server.cc#L1272]
[https://github.com/apache/impala/blob/bb610dee09a8069bb993b4c668f7e481c1774b70/be/src/service/impala-server.cc#L2065]
These metrics are global metrics of the local catalog cache. They are not specifit to a single statement. It's a waste to update the metrics concurrently.
[https://github.com/apache/impala/blob/bb610dee09a8069bb993b4c668f7e481c1774b70/be/src/service/impala-server.cc#L1526-L1559]
We've seen "hanging issues" that all statements, including the catalog update thread, are slowly executing the UpdateCatalogMetrics() function. See details in the attached jstack dump.
Indeed, if one thread is running the UpdateCatalogMetrics() function, the other threads can skip it and move forward.
was:
Impala coordinator tracks local metrics of the catalog, e.g. number of dbs/tables. When use_local_catalog is enabled, it also tracks the cache metrics, e.g. cache hit/miss count/rate.
These metrics are updated at the end of each statement, even for simple statements like "USE <db>", "SET var=xxx", "SELECT 1". The catalog update thread will also update the metrics in the end.
https://github.com/apache/impala/blob/bb610dee09a8069bb993b4c668f7e481c1774b70/be/src/service/impala-server.cc#L1272
https://github.com/apache/impala/blob/bb610dee09a8069bb993b4c668f7e481c1774b70/be/src/service/impala-server.cc#L2065
These metrics are global metrics of the local catalog cache. They are not specifit to a simple statement. It's a waste to update the metrics concurrently.
https://github.com/apache/impala/blob/bb610dee09a8069bb993b4c668f7e481c1774b70/be/src/service/impala-server.cc#L1526-L1559
We've seen "hanging issues" that all statements, including the catalog update thread, are slowly executing the UpdateCatalogMetrics() function. See details in the attached jstack dump.
Indeed, if one thread is running the UpdateCatalogMetrics() function, the other threads can skip it and move forward.
> Skip UpdateCatalogMetrics if another thead is on-going in it
> ------------------------------------------------------------
>
> Key: IMPALA-11409
> URL: https://issues.apache.org/jira/browse/IMPALA-11409
> Project: IMPALA
> Issue Type: Improvement
> Components: Backend
> Reporter: Quanlong Huang
> Assignee: Quanlong Huang
> Priority: Critical
> Attachments: jstack-1.txt
>
>
> Impala coordinator tracks local metrics of the catalog, e.g. number of dbs/tables. When use_local_catalog is enabled, it also tracks the cache metrics, e.g. cache hit/miss count/rate.
> These metrics are updated at the end of each statement, even for simple statements like "USE <db>", "SET var=xxx", "SELECT 1". The catalog update thread will also update the metrics in the end.
> [https://github.com/apache/impala/blob/bb610dee09a8069bb993b4c668f7e481c1774b70/be/src/service/impala-server.cc#L1272]
> [https://github.com/apache/impala/blob/bb610dee09a8069bb993b4c668f7e481c1774b70/be/src/service/impala-server.cc#L2065]
> These metrics are global metrics of the local catalog cache. They are not specifit to a single statement. It's a waste to update the metrics concurrently.
> [https://github.com/apache/impala/blob/bb610dee09a8069bb993b4c668f7e481c1774b70/be/src/service/impala-server.cc#L1526-L1559]
> We've seen "hanging issues" that all statements, including the catalog update thread, are slowly executing the UpdateCatalogMetrics() function. See details in the attached jstack dump.
> Indeed, if one thread is running the UpdateCatalogMetrics() function, the other threads can skip it and move forward.
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