> -----Original Message-----
> From: pgsql-hackers-owner(at)postgresql(dot)org
> [mailto:pgsql-hackers-owner(at)postgresql(dot)org] On Behalf Of Robert Haas
> Sent: Monday, February 20, 2017 2:20 AM
> To: Kaigai Kouhei(海外 浩平) <kaigai(at)ak(dot)jp(dot)nec(dot)com>
> Cc: Claudio Freire <klaussfreire(at)gmail(dot)com>; Amit Kapila
> <amit(dot)kapila16(at)gmail(dot)com>; pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
> Subject: Re: ParallelFinish-hook of FDW/CSP (Re: [HACKERS] Steps inside
> On Fri, Feb 17, 2017 at 12:46 PM, Kouhei Kaigai <kaigai(at)ak(dot)jp(dot)nec(dot)com>
> > The attached patch is revised one.
> > Invocation of Exec(Foreign|Custom)ParallelFinish was moved to
> > ExecParallelRetrieveInstrumentation() not to walk on the plan- state
> > tree twice.
> > One (hypothetical) downside is, FDW/CSP can retrieve its own run-time
> > statistics only when query is executed under EXPLAIN ANALYZE.
> > This enhancement allows FDW/CSP to collect its specific run- time
> > statistics more than Instrumentation, then show them as output of
> > EXPLAIN. My expected examples are GPU's kernel execution time, DMA
> > transfer ratio and so on. These statistics will never appear in the
> > Instrumentation structure, however, can be a hot- point of performance
> > bottleneck if CustomScan works on background workers.
> Would gather_shutdown_children_first.patch from
> help with this problem also? Suppose we did that, and then also added an
> ExecShutdownCustom method. Then you'd definitely be able to get control
> before the DSM went away, either from ExecEndNode() or ExecShutdownNode().
Ah, yes, I couldn't find any problem around the above approach.
ExecShutdownGather() can be called by either ExecShutdownNode() or
ExecEndGather(). This patch allows to have an entrypoint for CSP/FDW
prior to release of the DSM.
PG-Strom Project / NEC OSS Promotion Center
KaiGai Kohei <kaigai(at)ak(dot)jp(dot)nec(dot)com>
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