Re: AIX and Interix also do early PID recycling.

[Roman Rakus]

On 08/01/2012 03:13 PM, Chet Ramey wrote:
> On 7/30/12 10:41 AM, Roman Rakus wrote:
>
> > Hmm... I don't know much about boundaries of maximum number of user
> > processes. But anyway - do you think that (re)changing js.c_childmax (when
> > `ulimit -u' is changed) is not good?
> Maybe it's ok up to some fixed upper bound.  But if you're going to have
> that fixed upper bound, why not just use it as the number of job exit
> statuses to remember all the time?
I prepared a patch which add configure option to enable and set the 
number of job exit statuses to remember.
I found that posix is talking about changing system configurable 
variables and values; quoting:
"""
This runtime facility is not meant to provide ever-changing values that 
applications have to check multiple times. The values are seen as 
changing no more frequently than once per system initialization, such as 
by a system administrator or operator with an automatic configuration 
program. This volume of POSIX.1-2008 specifies that they shall not 
change within the lifetime of the process.
"""
(see http://pubs.opengroup.org/onlinepubs/9699919799/functions/sysconf.html)
So I would tell that bash does not need to check every time maxchild value.
However, when the maxchild is set to unlimited, now the bash will use 
predefined DEFAULT_CHILD_MAX which is set to 32.
The attached patch adds ability to set forced number of remembered 
statuses, easily during configure time, example:
 ./configure --enable-fixedjsmax=2048
It will force bash to remember 2048 statuses, independently on childmax 
value.
Patch should clearly apply to git master branch.
Chet, what do you think about it?

RR

0001-Option-to-use-fixed-number-of-remembered-job-exit-st.patch
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