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Posted to issues-all@impala.apache.org by "Zoltán Borók-Nagy (JIRA)" <ji...@apache.org> on 2018/09/06 10:38:00 UTC
[jira] [Assigned] (IMPALA-7542) find-fragment-instances in
impala-gdb.py misses to find the "root threads"
[ https://issues.apache.org/jira/browse/IMPALA-7542?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Zoltán Borók-Nagy reassigned IMPALA-7542:
-----------------------------------------
Assignee: Zoltán Borók-Nagy
> find-fragment-instances in impala-gdb.py misses to find the "root threads"
> --------------------------------------------------------------------------
>
> Key: IMPALA-7542
> URL: https://issues.apache.org/jira/browse/IMPALA-7542
> Project: IMPALA
> Issue Type: Bug
> Reporter: Zoltán Borók-Nagy
> Assignee: Zoltán Borók-Nagy
> Priority: Major
>
> find-fragment-instances uses ThreadDebugInfo from IMPALA-6416 to find the query ids and fragment ids currently being executed of an (probably crashed) impalad.
> To achieve that it traverses the stack frames of each thread and searches for the stack frame of Thread::SuperviseThread(). This function has a parent_thread_info parameter that points to its parent thread's ThreadDebugInfo object. Then, checks what instance id the parent thread is working on.
> This is all good until the bottom of the thread hierarchy because threads always work on the same fragment instance that their parent work on.
> However, at the top of the hierarchy there is some "root thread" that starts to work on a fragment instance, but its parent doesn't work on any. Since we only check the parent thread's instance id we miss to catch this first thread.
> Thread::SuperviseThread() also has a local ThreadDebugInfo that contains the proper instance id, so we should use it instead of the parent's.
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