From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
cc: "Henrik Cednert (Filmlance)" <henrik.cednert@filmlance.se>,
        "pgsql-performance@lists.postgresql.org"
 <pgsql-performance@lists.postgresql.org>
Subject: Re: pg_dump 3 times as slow after 8.4 -> 9.5 upgrade
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Comments: In-reply-to Robert Haas <robertmhaas@gmail.com>
	message dated "Tue, 21 Nov 2017 13:39:26 -0500"
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Date: Tue, 21 Nov 2017 13:46:09 -0500
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Robert Haas <robertmhaas@gmail.com> writes:
> On Tue, Nov 21, 2017 at 12:01 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Can you get a profile of where the machine is spending its time during the
>> dump run?  On Linux I'd recommend "perf", but on macOS, hmm ...
>> You could use Activity Monitor, but as far as I can see that just captures
>> short-duration snapshots, which might not be representative of a 10-hour
>> run.  XCode's Instruments feature would probably be better about giving
>> a full picture, but it has a steep learning curve.

> macOS's "sample" is pretty easy to use and produces text format output
> that is easy to email.

Ah, good idea.  But note that only traces one process, so you'd need to
first determine whether it's pg_dump or the backend that's eating most
of the CPU.  Or sample both of them.

			regards, tom lane