From: cvadr014@vmsb.is.csupomona.edu
Newsgroups: comp.os.os2.advocacy,comp.os.os2.misc
Subject: Re: OS/2 Crashproof? NOT!
Date: 18 Nov 92 06:43:26 GMT
Organization: California State Polytechnic University, Pomona
Nntp-Posting-User: cvadr014

In article <1992Nov16.163952.5841@ais.com>, bruce@ais.com (Bruce C. Wright) writes:
> In article <1992Nov16.164438.27020@njitgw.njit.edu>, dic5340@hertz.njit.edu (David Charlap) writes:
>> In article <BxsoLo.qF@csfb1.fir.fbc.com> uunet!csfb1!jbrock writes:
>>>
>>>I'm sorry, but I do a lot of work on an IBM mainframe running VM/CMS,
>>>and an application running in a virtual machine just does not crash the
>>>system (unless the machine has special privileges), no matter how badly
>>>behaved it is.  I can forgive UNIX for being crashable (it's *old*),
>>>but I don't think a normal application (as opposed to a device driver
>>>or something that touches the hardware directly) should ever be able to
>>>crash a fully modern operating system.  We should have *something* to
>>>show for all these years of operating system experience, shouldn't we?
>> 
>> VM/CMS is much more limited.  You don't have the ability to spawn
>> additional processes or create additional virtual machines (that
>> requires editing system parameter tables and re-IPLing the system).
>> Under Unix, any process can spawn additional processes, each getting a
>> slice of CPU time.
>> 
>> This will kill any Unix system:
>> 
>> 	while (1) fork();
>> 
>> Such a thing can be done on most multitasking systems, and will kill
>> any OS that allows user-level processes to spawn child processes.
> 
> Only true if the fork() is allowed to succeed until all system resources
> are exhausted.  Some multiuser systems put a quota on the number of
> processes each user can create, which prevents one user from hogging
> all of the available process slots/system dynamic memory (or however
> the particular OS keeps track of multiple processes). 
> 
> And even on a single-user OS, you could put limits on the number of
> processes (either a limit on the total number of processes or on the
> number of processes in a particular process tree).  Obviously you
> couldn't start up _new_ processes if a program like this hogged all
> the slots, but if you could get to a suitable task manager process
> you could kill the offending process(es).
> 
> Bruce C. Wright
-- 
	I believe that the # of processes (threads) is initialy set at boot by
THREADS= in config.sys - but that can be overriden if i remeber corectly - I
don't have my MS-Progr Ref for Os/2 handy - but isn't there a function to
change that? now - assuming you run out of threads to create, the 'runaway'
program will not be able to create any more, however, if you can reset it -
then the run away program would be able to go on wouldn't it?

	but the point here is - that if you TRY - you can crash ANY operating
system - (ok - i'll leave the VM/CMS systems outta this) - Dos, Windoze, Os/2,
Unix, VMS, Amiga, Mac, you name it, it can be crashed - if you try - 


---
Nick Steel
Email: cvadr014@vmsa.is.csupomona.edu
Phone: 714-594-8201

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