On Mon, Oct 17, 2016 at 6:22 AM, Kouhei Kaigai <kai...@ak.jp.nec.com> wrote: > Hello, > > I'm now trying to carry extra performance statistics on CustomScan > (like DMA transfer rate, execution time of GPU kernels, etc...) > from parallel workers to the leader process using the DSM segment > attached by the parallel-context. > We can require an arbitrary length of DSM using ExecCustomScanEstimate > hook by extension, then it looks leader/worker can share the DSM area. > However, we have a problem on this design. > > Below is the implementation of ExecEndGather(). > > void > ExecEndGather(GatherState *node) > { > ExecShutdownGather(node); > ExecFreeExprContext(&node->ps); > ExecClearTuple(node->ps.ps_ResultTupleSlot); > ExecEndNode(outerPlanState(node)); > } > > It calls ExecShutdownGather() prior to the recursive call of ExecEndNode(). > The DSM segment shall be released on this call, so child node cannot > reference the DSM at the time of ExecEndNode(). >
Before releasing DSM, we do collect all the statistics or instrumentation information of each node. Refer ExecParallelFinish()->ExecParallelRetrieveInstrumentation(), so I am wondering why can't you collect the additional information in the same way? -- With Regards, Amit Kapila. EnterpriseDB: http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers