Re: valgrind vs. shared typmod registry

From: Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>
To: Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>
Cc: pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: valgrind vs. shared typmod registry
Date: 2017-09-16 20:49:22
Message-ID: CAEepm=2ekM7BFdpZHqsJhfrewb7FndhEPPhDQ4QnTGNgSB4tQw@mail.gmail.com
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On Sun, Sep 17, 2017 at 7:42 AM, Thomas Munro
<thomas(dot)munro(at)enterprisedb(dot)com> wrote:
> On Sun, Sep 17, 2017 at 12:30 AM, Tomas Vondra
> <tomas(dot)vondra(at)2ndquadrant(dot)com> wrote:
>> I've been running some regression tests under valgrind, and it seems
>> select_parallel triggers some uses of uninitialized values in dshash. If
>> I'm reading the reports right, it complains about hashtable->size_log2
>> being not being initialized in ensure_valid_bucket_pointers.
>
> Thanks. Will investigate.

Yeah, it's a bug, I simply failed to initialise it.
ensure_valid_bucket_pointers() immediately fixes the problem (unless
the uninitialised memory had an unlikely value), explaining why it
works anyway. I'm a bit tied up today but will test and post a patch
tomorrow.

--
Thomas Munro
http://www.enterprisedb.com

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