Date: Fri, 4 Nov 2016 15:14:31 +0100 From: Solar Designer <solar@...nwall.com> To: john-users@...ts.openwall.com Subject: Re: John does not fork as many times as I want On Fri, Nov 04, 2016 at 02:59:10PM +0100, matlink wrote: > I've omitted to tell something: > > after these missing forks, the main process returns me: > > 1:Fork: cannot allocate memory > > which explains why all forks are not poped. Oh, sure. Sounds like you're cracking the full(er) LinkedIn dump than was circulating in 2012, then, and your use of the "-linkedin" format is inappropriate. Please use the simple "raw-SHA1" format instead. And please use bleeding-jumbo. > However it seems that I > still have plenty of available memory (about 200GB free). You say you're requesting 40 forks, but only 5 processes are left. This may mean that some of the other 35 were forked, fought for memory, and then died - freeing up that 200 GB that you see. > Can this error come from another situation than lack of memory? There are many other possibilities, but they are not likely in your case. The way "--fork" works, it does not multiply the memory needs of one process by the number of processes right away. Most of the memory pages are shared between the processes. However, when a lot of passwords get cracked, the differences between the processes increase, and fewer pages are shared. Thus, when cracking large password hash dumps like this, you need to start with fewer forked processes to get the easiest passwords cracked first, then after a few hours or days, when there are relatively few hashes left to crack (e.g., 20% of original) and the successful guesses are not as frequent, restart with your desired number of processes. There were some changes in bleeding-jumbo (since 1.8.0-jumbo-1) that should partially mitigate this issue, so maybe you'd be able to run more processes with it now, but overall my suggested approach above is still the way to go. Alexander
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