From: Craig James <craig_james@emolecules.com>
To: pgsql-performance@postgresql.org
Subject: Re: pg_connect takes 3.0 seconds
Date: Wed, 06 Jan 2010 10:31:12 -0800
Message-ID: <4B44D6F0.3090107@emolecules.com> (raw)
In-Reply-To: <ca24673e1001060904wab83fe0ne7277daf02b1080@mail.gmail.com>
References: <daed64561001041812s602a3098l686f630d6448835f@mail.gmail.com>
<ca24673e1001060904wab83fe0ne7277daf02b1080@mail.gmail.com>
Dave Crooke wrote:
> The fact that the delays are clustered at (3 + 0.2 n) seconds, rather
> than a distributed range, strongly indicates a timeout and not
> (directly) a resource issue.
>
> 3 seconds is too fast for a timeout on almost any DNS operation, unless
> it has been modified, so I'd suspect it's the TCP layer, e.g. perhaps
> the SYN packet goes awol and it has to retry.
>
> I'd second the vote for investigation with a packet sniffing tool
> (Wireshark, tcpdump, etc)
If you have a PC (Windows), pingplotter is a remarkable and simple tool to use that quickly identifies problems, and gives results that are convincing when you show them to your network admin. Wireshark and tcpdump have a pretty steep learning curve and are overkill if your problem is simple.
Craig
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To: pgsql-performance@postgresql.org
Cc: craig_james@emolecules.com
Subject: Re: pg_connect takes 3.0 seconds
In-Reply-To: <4B44D6F0.3090107@emolecules.com>
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