| Gavin W. Burris on 18 Apr 2016 12:32:51 -0700 |
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| Re: [PLUG] >32K concurrent processes |
Hi, Bhaskar. This sounds really neat. Why do you need to simultaneously serialize ALL transactions? For instance, my bank balance or my medical records have absolutely no real-time serial dependencies on any other account. Maybe a service free on my medical record is a dependency, but just update those daily. My balance may depend on a transfer, but just look at the posted timestamp. If one needs a bank-wide report, again, just look at transactions to a specific timestamp. What is an acceptable granularity? Sure, you can get millisecond accuracy this way, but why would you want that given the downsides? Is this some kind of high-frequency trading scheme? If so, any further communications will have to be under billable hours for my private consulting services. :D Cheers. On Mon 04/18/16 02:44PM EDT, K.S. Bhaskar wrote: > This is not a distributed environment - it's a single system. The reason is > transaction serialization. When every transaction can potentially depend on > the result of the preceding transaction, the more you can centralize > serialization decision making, the faster you can make decisions required > to ensure ACID properties at transaction commit time. With GT.M, this > serialization is done in the shared memory of a single computing node. Even > with technologies such as RDMA over Infiniband, IPC between processes on > different nodes is one to two orders of magnitude slower than processes on > a single node. So, as long as throughput is not constrained by the amount > of CPU, RAM, or IO you can put on a single node, centralized serialization > gives you the best overall throughput. With GT.M, and with the types of > computer system you can purchase today, the throughput you can achieve on a > single node is big enough to handle the needs of real-time core-processing > (a core system is the system of record for your bank balance) on just about > any bank. The largest real-time core systems in production anywhere in the > world today that I know of run on GT.M - these are systems with over 30 > million accounts. In healthcare, the real-time electronic health records > for the entire Jordanian Ministry of Health system are being rolled out on > a single system (⅓ of the electronic health records for a country with the > area and population of Indiana processed on a single system). > > What people think of as a horizontally scalable architecture for a > transactional system is stateless application servers that can be spun up > as needed, but which send all the needed state to a database under the > covers. This architecture scales only as well as the database scales on a > single node, which is to say not very well - in our testing some years ago, > we found that because of transaction serialization, a popular database > scaled better on a single node than across multiple nodes in a cluster. > > So thanks for all the suggestions but for now, the specific information I > need is how to configure a Linux system to allow more than 32K concurrent > processes. Increasing pid_max is a necessary change, but clearly not a > sufficient change. > > Regards > -- Bhaskar > > > > On Mon, Apr 18, 2016 at 12:19 PM, Keith C. Perry <kperry@daotechnologies.com > > wrote: > > > Bhasker, > > > > What's the deployment infrastructure? When you say "We're trying to run a > > workload that simulates a large number of concurrent users (as you might > > find at a large financial or healthcare institution)", it makes me think > > that is more a distributed environment where you need a large number of > > clients being serviced by a pool of servers. > > > > If that is the case it sound more like you would need a listener (server) > > running that would then fork off or thread child connections to respond to > > client requests. This is also something that can be achieved in a local > > context the listener on the localhost IP or using unix sockets. > > > > > > ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ > > Keith C. Perry, MS E.E. > > Owner, DAO Technologies LLC > > (O) +1.215.525.4165 x2033 > > (M) +1.215.432.5167 > > www.daotechnologies.com > > > > ------------------------------ > > *From: *"K.S. Bhaskar" <bhaskar@bhaskars.com> > > *To: *"Philadelphia Linux User's Group Discussion List" < > > plug@lists.phillylinux.org> > > *Sent: *Monday, April 18, 2016 11:49:19 AM > > *Subject: *Re: [PLUG] >32K concurrent processes > > > > Thanks for the suggestions, Gavin, but batching the load won't work in > > this case. We're trying to run a workload that simulates a large number of > > concurrent users (as you might find at a large financial or healthcare > > institution) all of whom expect the system to respond immediately when they > > ask it to do something. I intend to play with the scheduler. > > > > Regards > > -- Bhaskar > > > > > > On Mon, Apr 18, 2016 at 9:13 AM, Gavin W. Burris <bug@wharton.upenn.edu> > > wrote: > > > >> Good morning, Bhaskar. > >> > >> Have you considered using /dev/shm aka tmpfs for shared memory on Linux? > >> Maybe stage all required files there and make sure you are read-only where > >> possible. > >> > >> With so many processes, your system is just constantly changing threads. > >> Assuming you are not oversubscribing RAM (32GB / 32k is less than 1MB per), > >> you will want to tune the kernel scheduler. > >> > >> https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Performance_Tuning_Guide/sect-Red_Hat_Enterprise_Linux-Performance_Tuning_Guide-CPU-Configuration_suggestions.html#sect-Red_Hat_Enterprise_Linux-Performance_Tuning_Guide-Configuration_suggestions-Tuning_scheduling_policy > >> > >> This very much sounds like an HPC problem (high-performance computing), > >> so my initial reaction is why not use a resource manager tuned for > >> high-throughput? Take a look at Open Grid Scheduler ( > >> http://gridscheduler.sourceforge.net/), an open source version of Grid > >> Engine. This will give you a layer of control, a job queue, where you > >> could then do a task array. Maybe you could launch 1000 jobs that iterate > >> 320 times? The job queue could then be tuned to not overload the system > >> and keep the system maximally / optimally utilized, aka don't run > >> everything at once but place it in a queue that runs through what you need > >> as resources are available. I would strongly consider using Grid Engine, > >> expecially given your statement that the procs "do a teeny bit of activity > >> every 10 seconds." > >> > >> Cheers. > >> > >> On Sun 04/17/16 11:12AM EDT, K.S. Bhaskar wrote: > >> > Thanks for the links Rohit. I'll check them out. The storage is SSD, the > >> > processes do minimal IO - I'm just trying to establish the ability to > >> have > >> > a file open by more than 32K processes, and I'm clearly running into a > >> > system limit. This is a development machine (16 cores, 32GB RAM - the > >> > production machine has something like 64 cores and 512GB RAM), but I > >> can't > >> > get you access to poke around because it is inside a corporate network. > >> > > >> > However, as the software is all open source, I can easily help you get > >> set > >> > up to poke around using your own system, if you want. Please let me > >> know. > >> > > >> > Regards > >> > -- Bhaskar > >> > > >> > > >> > On Sun, Apr 17, 2016 at 10:54 AM, Rohit Mehta <ro@paper-mill.com> > >> wrote: > >> > > >> > > Some kernel parameters to research (which may not be right for your > >> > > application) > >> > > > >> > > > >> https://www.debian-administration.org/article/656/Installing_Oracle11_and_Oracle12_on_Debian_Wheezy_Squeeze > >> > > and /etc/security.conf changes > >> > > > >> http://stackoverflow.com/questions/9361816/maximum-number-of-processes-in-linux > >> > > > >> > > Do these process do a lot of IO? Is your storage rotational media or > >> > > SSD? Can your application run off ramdisk storage? Have you tried > >> > > enabling hyperthreading? > >> > > > >> > > Do you have the ability to test application loads non-production > >> system? > >> > > If so i'd be interesting in helping you poke around. It might be an > >> > > education for me. > >> > > > >> > > > >> > > On Sun, Apr 17, 2016 at 10:42 AM, Rohit Mehta <ro@paper-mill.com> > >> wrote: > >> > > > >> > >> Back many years ago, I installed Oracle on my Debian workstation for > >> fun, > >> > >> and I remember the guide had a lot of tweaks. "ulimit" is one that > >> I can > >> > >> think of, but I don't remember them all. I'm poking around the > >> internet to > >> > >> see if I can find the oracle guide (although it might not be > >> relevant on > >> > >> newer kernels) > >> > >> > >> > >> On Sun, Apr 17, 2016 at 10:27 AM, K.S. Bhaskar <bhaskar@bhaskars.com > >> > > >> > >> wrote: > >> > >> > >> > >>> Thanks Steve, but in this case we have a customer need to crank up > >> the > >> > >>> number of processes on Linux. > >> > >>> > >> > >>> Regards > >> > >>> -- Bhaskar > >> > >>> > >> > >>> On Sat, Apr 16, 2016 at 4:09 PM, Steve Litt < > >> slitt@troubleshooters.com> > >> > >>> wrote: > >> > >>> > >> > >>>> On Fri, 15 Apr 2016 17:40:09 -0400 > >> > >>>> "K.S. Bhaskar" <bhaskar@bhaskars.com> wrote: > >> > >>>> > >> > >>>> > I am trying to crank up more than 32K concurrent processes (the > >> > >>>> > processes themselves hang and do a teeny bit of activity every 10 > >> > >>>> > seconds). But the OS (64-bit Debian 8 - Jessie) stubbornly > >> refuses to > >> > >>>> > crank up beyond 32K-ish processes. pid_max is set to a very large > >> > >>>> > number (1M), so that's not it. Any suggestions on what limits to > >> look > >> > >>>> > for appreciated. Thank you very much. > >> > >>>> > >> > >>>> This is old information, but back in the day people who wanted > >> lots and > >> > >>>> lots of processes used one of the BSDs to host that server. > >> > >>>> > >> > >>>> SteveT > >> > >>>> > >> > >>>> Steve Litt > >> > >>>> April 2016 featured book: Rapid Learning for the 21st Century > >> > >>>> http://www.troubleshooters.com/rl21 > >> > >>>> > >> > >>>> > >> ___________________________________________________________________________ > >> > >>>> Philadelphia Linux Users Group -- > >> > >>>> http://www.phillylinux.org > >> > >>>> Announcements - > >> > >>>> http://lists.phillylinux.org/mailman/listinfo/plug-announce > >> > >>>> General Discussion -- > >> > >>>> http://lists.phillylinux.org/mailman/listinfo/plug > >> > >>>> > >> > >>> > >> > >>> > >> > >>> > >> > >>> > >> ___________________________________________________________________________ > >> > >>> Philadelphia Linux Users Group -- > >> > >>> http://www.phillylinux.org > >> > >>> Announcements - > >> > >>> http://lists.phillylinux.org/mailman/listinfo/plug-announce > >> > >>> General Discussion -- > >> > >>> http://lists.phillylinux.org/mailman/listinfo/plug > >> > >>> > >> > >>> > >> > >> > >> > > > >> > > > >> ___________________________________________________________________________ > >> > > Philadelphia Linux Users Group -- > >> > > http://www.phillylinux.org > >> > > Announcements - > >> > > http://lists.phillylinux.org/mailman/listinfo/plug-announce > >> > > General Discussion -- > >> > > http://lists.phillylinux.org/mailman/listinfo/plug > >> > > > >> > > > >> > >> > > >> ___________________________________________________________________________ > >> > Philadelphia Linux Users Group -- > >> http://www.phillylinux.org > >> > Announcements - > >> http://lists.phillylinux.org/mailman/listinfo/plug-announce > >> > General Discussion -- > >> http://lists.phillylinux.org/mailman/listinfo/plug > >> > >> > >> -- > >> Gavin W. Burris > >> Senior Project Leader for Research Computing > >> The Wharton School > >> University of Pennsylvania > >> Search our documentation: http://research-it.wharton.upenn.edu/about/ > >> Subscribe to the Newsletter: http://whr.tn/ResearchNewsletterSubscribe > >> > >> ___________________________________________________________________________ > >> Philadelphia Linux Users Group -- > >> http://www.phillylinux.org > >> Announcements - > >> http://lists.phillylinux.org/mailman/listinfo/plug-announce > >> General Discussion -- > >> http://lists.phillylinux.org/mailman/listinfo/plug > >> > > > > > > ___________________________________________________________________________ > > Philadelphia Linux Users Group -- > > http://www.phillylinux.org > > Announcements - > > http://lists.phillylinux.org/mailman/listinfo/plug-announce > > General Discussion -- > > http://lists.phillylinux.org/mailman/listinfo/plug > > > > ___________________________________________________________________________ > > Philadelphia Linux Users Group -- > > http://www.phillylinux.org > > Announcements - > > http://lists.phillylinux.org/mailman/listinfo/plug-announce > > General Discussion -- > > http://lists.phillylinux.org/mailman/listinfo/plug > > > > > ___________________________________________________________________________ > Philadelphia Linux Users Group -- http://www.phillylinux.org > Announcements - http://lists.phillylinux.org/mailman/listinfo/plug-announce > General Discussion -- http://lists.phillylinux.org/mailman/listinfo/plug -- Gavin W. Burris Senior Project Leader for Research Computing The Wharton School University of Pennsylvania Search our documentation: http://research-it.wharton.upenn.edu/about/ Subscribe to the Newsletter: http://whr.tn/ResearchNewsletterSubscribe ___________________________________________________________________________ Philadelphia Linux Users Group -- http://www.phillylinux.org Announcements - http://lists.phillylinux.org/mailman/listinfo/plug-announce General Discussion -- http://lists.phillylinux.org/mailman/listinfo/plug