Date: Fri, 10 Mar 2017 19:19:17 -0300
From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Amit Kapila <amit.kapila16@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>,
	Michael Paquier <michael.paquier@gmail.com>,
	Dilip Kumar <dilipbalaut@gmail.com>,
	Tomas Vondra <tomas.vondra@2ndquadrant.com>,
	Jim Nasby <Jim.Nasby@bluetreble.com>,
	Andres Freund <andres@anarazel.de>,
	pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: Speed up Clog Access by increasing CLOG buffers
Message-ID: <20170310221917.dijugbcqym35of7o@alvherre.pgsql>
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Robert Haas wrote:

> The smoking gun was in 009_twophase_slave.log:
> 
> TRAP: FailedAssertion("!(nsubxids == MyPgXact->nxids)", File:
> "clog.c", Line: 288)
> 
> ...and then the node shuts down, which is why this hangs forever.
> (Also... what's up with it hanging forever instead of timing out or
> failing or something?)

This bit my while messing with 2PC tests recently.  I think it'd be
worth doing something about this, such as causing the test to die if we
request a server to (re)start and it doesn't start or it immediately
crashes.  This doesn't solve the problem of a server crashing at a point
not immediately after start, though.

(It'd be very annoying to have to sprinkle the Perl test code with
"assert $server->islive", but perhaps we can add assertions of some kind
in PostgresNode itself).

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services


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