I often write “solve hard math problem” codes and miss my Google days of lusting for a data center in bring up with 20K idle CPUs. My home computers always run at 100% and I have an AWS large instance as well. Looking forward to AMD’s 2x64 Rome.
On Sun, Jan 27, 2019 at 12:38 PM robert engels <reng...@ix.netcom.com> wrote: > Even with 64 cores your process takes 3hrs… unless they are all external > requests - so essentially unlimited cores. > > > On Jan 27, 2019, at 2:32 PM, Michael Jones <michael.jo...@gmail.com> > wrote: > > Glad you saw it. Lots of ways to do it but small-seeming details shape the > approach: > > Are the tasks of similar effort? If yes, good, if not it is VERY desirable > to start the hard ones first and on different workers. > > Do you know how many tasks? If you do not—if you only know when you’re > done with new tasks—then that means you need to signal completion. > > Can you wait for the last result before sending the first output? Could > mean a big stall and is very different than the single-thread case, but, it > allows sorting and easy load balancing. > > Might you want to quit early and abandon processing? This is not so > natural to the mechanisms so requires finesse in your code (as suggested by > various debates about the context idea). > > My snippet is one path through this decision matrix. > > Also, it uses an outer ask/answer channel pair for uniformity between > serial and parallel modes. This is fine for my case (ten thousand minute > long tasks) with a max rate of channel sending on my laptop of about 3M > sends/sec. overhead here is about zero but if the tasks were itsy-bitsy > then the overhead would matter. So you’d want to batch them—or restructure. > > On Sun, Jan 27, 2019 at 3:51 AM Tom Payne <twpa...@gmail.com> wrote: > >> Yes, I did, thank you! My reply was to the previous message (robert >> engels' post about it being "straightforward" but not providing code) and I >> think we just both hit send at about the same time. >> >> On Sat, 26 Jan 2019 at 02:52, Michael Jones <michael.jo...@gmail.com> >> wrote: >> >>> Did you notice that I sent you the complete code above? >>> >>> On Fri, Jan 25, 2019 at 2:48 PM <twpa...@gmail.com> wrote: >>> >>>> For what it's worth >>>> http://www.golangpatterns.info/concurrency/parallel-for-loop >>>> implements an order-preserving parallel map, but does not limit the >>>> number of workers. >>>> >>>> In my case, I want to limit the number of workers because I'm making a >>>> lot of system calls and don't want to overload the kernel. runtime.NumCPU() >>>> seems like a reasonable limit. >>>> >>>> >>>> >>>> On Friday, January 25, 2019 at 8:04:31 PM UTC+1, twp...@gmail.com >>>> wrote: >>>>> >>>>> Hi, >>>>> >>>>> I have a number of slow tasks that I want to run concurrently across >>>>> runtime.NumCPU() workers in a single process. The tasks have a specific >>>>> input order, but they are completely independent of each other and can >>>>> execute in any order. I would like to print the output of each task in the >>>>> same order as the input order of tasks. >>>>> >>>>> This can be implemented by including each task's index in the input >>>>> order as it is distributed via a channel to the workers, and the final >>>>> collection of results assembled using these task indexes before the >>>>> results >>>>> are printed. >>>>> >>>>> Assumptions: >>>>> - Small number of tasks (~10,000 max), i.e. this easily fits in memory. >>>>> - Single Go process, i.e. I don't want/need a distributed system. >>>>> >>>>> This feels like it should be common problem and there's probably >>>>> either a library or a standard Go pattern out there which can do it. My >>>>> web >>>>> search skills didn't find such a library though. Do you know of one? >>>>> >>>>> Cheers, >>>>> Tom >>>>> >>>>> >>>>> Background info to avoid the XY problem <http://xyproblem.info/>: >>>>> this is to make chezmoi <https://github.com/twpayne/chezmoi> run >>>>> faster. I want to run the doctor checks >>>>> <https://github.com/twpayne/chezmoi/blob/ed27b49f9ca4cd3662e6a59908dee24b0d295b79/cmd/doctor.go#L102-L163> >>>>> (basically os.Exec'ing a whole load of binaries to get their versions) >>>>> concurrently in the short term. In the long term I want to make chezmoi's >>>>> apply concurrent, so it runs faster too. In the first case, the order >>>>> requirement is because I want all users to see the output in the same >>>>> order >>>>> so that it's easy to compare. In the second case, the order requirement >>>>> comes because I need to ensure that parent directories are in the correct >>>>> state before checking their children. >>>>> >>>> >>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "golang-nuts" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to golang-nuts+unsubscr...@googlegroups.com. >>>> For more options, visit https://groups.google.com/d/optout. >>>> >>> >>> >>> -- >>> >>> *Michael T. jonesmichael.jo...@gmail.com <michael.jo...@gmail.com>* >>> >> -- > > *Michael T. jonesmichael.jo...@gmail.com <michael.jo...@gmail.com>* > > -- > You received this message because you are subscribed to the Google Groups > "golang-nuts" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to golang-nuts+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > > > -- *Michael T. jonesmichael.jo...@gmail.com <michael.jo...@gmail.com>* -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
