Re: libct ct_connect thread_safe

I my case I have n servers that I am connecting to with 1 connection per 
server.

- Mitch

On 12/14/2011 10:16 PM, James K. Lowden wrote:
> On Wed, 14 Dec 2011 16:18:23 -0700
> Mitch Freed<[email protected]>  wrote:
>
>> Is ct_connect (libct) not thread-safe?
> ...
>> I have seen the FAQ indicating that the threads cannot share a
>> CS_CONNECTION, which they do not in my case.
>
> I don't understand those two statements.  ct_connect() takes a
> CS_CONNECTION* as its first argument.  "Cannot share a connection"
> means cannot use a single CS_CONNECTION struct in more than one
> thread.  Calling ct_connect() *is* using that connection.
>
> So, no, I guess you'd have to say ct_connect() is not thread-safe.  Not
> that it should be, either!
>
> I would be curious to know (from anyone) why you use
> more than one thread to interact with a server connection.  The server
> is I/O bound by the network.  The client is certainly faster or, if not,
> two threads won't be faster than one.
>
> The only answer I know of is when the client is some kind of
> multithreaded something (a webserver, say) sharing a smaller number
> of database connections.
>
> But why?  In the vast majority of cases, that is a false economy: the
> overhead of making connections and of the server supporting 1:1
> connections/thread is negligible.  How do I know?  Because the vast
> majority of websites are small and slow.
>
> Unless you're measuring response times in milliseconds, what
> difference can the time it takes to connect to the server possibly
> make?  As soon as you accept the connect-time overhead, you know that
> every connection is needed, and that therefore if the database server
> can't support those connections, you need one that can.  (Probably you
> need more RAM.)
>
> Maybe you're reading this, saying to yourself that you can't wait for
> the time it takes to log in.  If so, I'd like to understand why not.
> Really.  I know sites like Google have scale and throughput issues that
> require sophistication.  But I also know most sites aren't a big as
> Google.
>
> My test database server is ~300 ms away, round trip, says ping.
> time(1) reports I can ping it 100 times in ~50 seconds (using a loop in
> bash).  That same loop lets me log in 100 times in ~60 seconds using
> tsql.  That puts each ping, allowing bash overhead, etc., at 500 ms,
> and each login at 600 ms, or 100 ms to log in.  That's consistent with
> my experience at work; I've never used a server where login times were
> significant.  Or a webserver with latency in that neighborhood,
> either, for that matter.
>
> What am I overlooking?  I'd bet 9 in 10 webservers not using 1:1
> database connections are wasting time engineering something that
> doesn't need engineering. Would someone please tell Mitt Romney?  I
> hear tell he's a betting man.
>
> --jkl
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