Bug#979682: startpar: Is it running anything in parallel?

[The Wanderer]

On 2021-01-09 at 18:56, Michael Krylov wrote:

> Package: startpar
> Version: 0.61-1
> Severity: important

This version is present in current Debian stable, but there is a newer
version available in current testing and unstable: 0.64-3.

> Dear Maintainer,

(Disclaimer: I am not a startpar maintainer as such, only an interested
bystander. As such, I have no specific startpar expertise to date, only
what I can observe and deduce.)

> I get a feeling that startpar doesn't work as it was intended.
> That is, it doesn't parallel the service starting at the boot.
> 
> I've conducted a couple of experiments: first, with makefile-style boot
> and startpar (the default one) and second, without startpar, by creating
> the /etc/init.d/.legacy-bootordering file.
> 
> Both of them yielded about the same time, 21±1 sec for me.
> 
> More than that, after reading its man page, I've tried to run startpar this way:
> 
> /lib/startpar/startpar sleep sleep sleep -a 10
> 
> And sure enough, it starts three sleep processes one by one and finishes after
> 30 seconds instead of 10.

On a computer tracking current Debian testing, with startpar 0.64-3, I
see:

$ time /bin/startpar sleep sleep sleep -a 10

real    0m10.006s
user    0m0.009s
sys     0m0.000s

$ time /bin/startpar sleep sleep -a 10

real    0m10.014s
user    0m0.012s
sys     0m0.000s

(Judging from the changelogs, the startpar binary was moved to /bin in
package version 0.63~beta-1.)

As such, I do not appear to encounter this behavior on my system.

> I might be wrong, but doesn't this mean that startpar is basically
> useless now?

The changelog for startpar 0.64 includes the following entry:

>> * Fixed regression which could cause jobs to run in serial (interactive
>>   mode) instead of parallel when devpts check failed. 
>>   Should greatly increase performance on affected systems.

I'd guess that you may be hitting this regression. If so, the problem
should be fixed in the currently latest startpar, although that version
is apparently not in current testing.

-- 
   The Wanderer

The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore all
progress depends on the unreasonable man.         -- George Bernard Shaw

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