[Israel.pm] Garbage Collection Question

Yuval Kogman lists at woobling.org
Mon May 10 10:34:03 PDT 2004


Try setting /proc/sys/mem/overcommit_whatever to 0.


On Mon, May 10, 2004 at 19:42:54 +0300, Yuval Yaari wrote:
> Isaac/Semuel, I think/hope that was sarcasm.
> 
> But yes, the only times I had to reboot my Linux box at work were 
> because of the kernel swapping [1].
> They were always hard reboots.
> Never because of Perl though.
> Getting MySQL to start swapping is easy, and if you put a too high 
> MaxClients in your httpd.conf, apache could swap easily.
> Just ab -c 10000 -n 10000000000 
> http://localhost/very/cpu/and/memory/intensive/mod_perl/or/cgi/.
> 
> Once I'd give my computer some time after it started swapping, but with 
> time, I learned to show mercy towards my computer, and just reboot.
> 
> To be honest, I'd rather see programs "crash", windows-style...
> 
>  --Yuval
> 
> [1] I'm not sure it was this machine but /sbin/modprobe didn't work one 
> time after re-compiling my kernel so I rebooted.
> 
> 
> Issac Goldstand wrote:
> 
> >AHHHHH!  You call that *positive*?!?  I'd rather a huge process in memory
> >than in swap any day!  Swapping makes everything on the system run slower.
> >
> > Yitzchak
> >
> >----- Original Message ----- 
> >From: "semuel" <semuel at semuel.co.il>
> >To: "'Perl in Israel'" <perl at perl.org.il>
> >Sent: Monday, May 10, 2004 8:13 PM
> >Subject: RE: [Israel.pm] Garbage Collection Question
> >
> >
> > 
> >
> >>Hello There.
> >>
> >>
> >>Why does everybody sees only the bad things?
> >>Think positively: the unwanted allocated memory won't be accessed, and the
> >>OS will eventually flash the inactive memory pages to the swap, where they
> >>will sleep until the application will need that memory again.
> >>No big deal.
> >>
> >>Semuel.
> >>
> >>
> >>-----Original Message-----
> >>From: perl-bounces at perl.org.il [mailto:perl-bounces at perl.org.il] On Behalf
> >>Of Jason Elbaum
> >>Sent: Sunday, May 09, 2004 11:45 AM
> >>To: Perl in Israel
> >>Subject: Re: [Israel.pm] Garbage Collection Question
> >>
> >>Yuval Yaari wrote:
> >>
> >>   
> >>
> >>>When that variable goes out of scope or is catched by the
> >>>garbage fairy, Perl will not release that 1MB to the kernel right away,
> >>>     
> >>>
> >it
> > 
> >
> >>>will reuse it in case it needs it later on during execution."
> >>>     
> >>>
> >>Many operating systems never really allow a process to return allocated
> >>memory to the OS until the process exits. Processes can only grow, not
> >>shrink. This may be due to an assumption that if a process once needed X
> >>MB, it will probably need it again some time, and the churn by
> >>repeatedly allocating and deallocating it to the process is more
> >>expensive to the OS than just leaving it there.
> >>
> >>As a rule of thumb, you're better off not allocating massive data
> >>structures unless you really need to access all the data at once.
> >>
> >>
> >>Jason Elbaum
> >>_______________________________________________
> >>Perl mailing list
> >>Perl at perl.org.il
> >>http://www.perl.org.il/mailman/listinfo/perl
> >>
> >>
> >>
> >>_______________________________________________
> >>Perl mailing list
> >>Perl at perl.org.il
> >>http://www.perl.org.il/mailman/listinfo/perl
> >>
> >>   
> >>
> >
> >_______________________________________________
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> >Perl at perl.org.il
> >http://www.perl.org.il/mailman/listinfo/perl
> >
> >
> > 
> >
> 
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-- 
 ()  Yuval Kogman <nothingmuch at woobling.org> 0xEBD27418  perl hacker &
 /\  kung foo master: /me climbs a brick wall with his fingers: neeyah!

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