From: | Andres Freund <andres(at)2ndquadrant(dot)com> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: Should PostgresMain() do a LWLockReleaseAll()? |
Date: | 2014-02-23 20:29:38 |
Message-ID: | 20140223202938.GA20412@awork2.anarazel.de |
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Lists: | pgsql-hackers |
On 2014-02-23 14:48:12 -0500, Tom Lane wrote:
> Andres Freund <andres(at)2ndquadrant(dot)com> writes:
> > Currently the error handling of normal backends only does a
> > LWLockReleaseAll() once CurrentTransactionState->state != TRANS_DEFAULT
> > because it's called in AbortTransaction(). There's pretty damn few
> > places that fiddle with lwlocks outside of a transaction command, but I
> > still do wonder whether it'd wouldn't be a tad more robust to
> > unconditionally do a LWLockReleaseAll(), just like other error handlers
> > are doing?
>
> Why do that thing in particular, and not all the other things that
> AbortTransaction() does?
Because the other things in AbortTransaction() should really only be
relevant inside a transaction, but there's valid reasons to use lwlocks
outside one.
E.g. I think that before Robert and I added a LWLockReleaseAll() to
WalSndErrorCleanup() the whole walsender code wasn't protected. I am not
entirely sure there's a real problem there in the backbranches, but it's
a fair amount of code, espcially around base backups...
Greetings,
Andres Freund
--
Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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