mysql-proxy-discuss team mailing list archive

[Kay Röpke <Kay.Roepke@xxxxxxx>]

On Jan 18, 2009, at 5:05 PM, Joshua Zhu wrote:

> Hi Kay,
> It seems that the flow of max-open-file option processing in your last
> commit was like this (non WIN32 systems, in pseudo code):
>    if the max-open-file-option is not set then
>        set the-limit-of-open-files = 8192
>    else
>        set the-limit-of-open-files = the-number-specified
>    end
> But I think it might be better if the flow is:
>    if the max-open-file-option is set then
>        set the-limit-of-open-files = the-number-specified
>    end
> Because IMHO, it should be okay if a user sets the max number of open
> files by using the ulimit(1) command but without setting the
> max-open-file option, no matter the number is greater than or less
> than 8192.
> In a word, we should only reset the value of RLIMIT_NOFILE when the
> max-open-file option is specified clearly.


In general I'd agree but this is one the ugly things that come up with  
us using the same code in the MySQL Enterprise Monitor:
Basically, we have customers who did not increase the max number of  
open files prior to starting the agent, and later on ran out of fds.
We wanted to have a solution that would set a "reasonable" default  
value, but for Windows I could not come up with a solution that  
increased the number in a script.
So, rather than doing the ulimit in a wrapper script and using a  
different approach for Windows, I've opted to do it in C for all  
platforms.
We chose 8192 simply because it's a nice enough and high enough  
number ;)
Perhaps this needs a bit more documentation, I'll raise the issue with  
our docs folks.

To reiterate: Some folks simply forget to raise ulimit -n, then run  
into problems in production, which we need to avoid. 8192 is  
reasonable, and you can still set it to whatever you want.
Perhaps the code should check if the current number is higher than  
8192 and not mess with it. Good idea, actually.

cheers,
-k
--
Kay Roepke
Software Engineer, MySQL Enterprise Tools

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