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We use asynchronous tasks in MirageOS (cooperative multitasking) using lwt http://ocsigen.org/lwt/latest/manual/manual http://ocsigen.org/lwt/latest/manual/manu

We use asynchronous tasks in MirageOS (cooperative multitasking) using lwt http://ocsigen.org/lwt/latest/manual/manual http://ocsigen.org/lwt/latest/manual/manual, so you can serve multiple network connections at the same time. Since there are no processes, there's no concept of "fork", but indeed you can run multiple tasks at the same time (using the same address space). Why again would you need multiple processes? Since the programming language OCaml has a semantics and is memory-safe, there's no strong reason for isolation at execution time (apart from the C bits, which we try to keep to a minimum and compile with runtime safety flags (red-zone for stack protection, mapping execute-only (seems to only reliably work on OpenBSD), etc.)).

asymmetric 5y ago
Is this also how you deal with logging/monitoring? Do you have a concept of logging daemon? How would I run prometheus exporter-like things? Is there a FAQ where questions along these lines are answered?
- avsm 5y ago
  Just substitute 'microservice' with 'unikernel' and you do broadly the same things. There's a prometheus library that you link with the MirageOS unikernel and it exports using that: https://github.com/mirage/prometheus https://github.com/mirage/prometheus No FAQ for this sort of thing yet, but we should start assembling one sometime soon. Questions like this very welcome on the discussion forums: https://discuss.ocaml.org/t/ann-mirageos-4-0/9598 https://discuss.ocaml.org/t/ann-mirageos-4-0/9598 to help us get started. There's a nice collection of unikernels over at: https://github.com/roburio/unikernels https://github.com/roburio/unikernels and https://github.com/tarides/unikernels https://github.com/tarides/unikernels for various infrastructure pieces (like https, smtp, dns, ip filters, etc) that are good to crib from for your own infrastructure.
- hannesm 5y ago
  Maybe https://hannes.robur.coop/Posts/Monitoring https://hannes.robur.coop/Posts/Monitoring sheds some light how to monitor MirageOS unikernels ;)
scns 5y ago
Conurrency instead of parallelism.
- wmf 5y ago
  No amount of concurrency on a single core can equal the performance of multiple cores.
  - pjmlp 5y ago
    That is why you deploy a process per core, with affinity so that it doesn't jump around.
  - cestith 5y ago
    You can run more than one unikernel per machine. That's why things like KVM or Bhyve are targets instead of just bare metal.
gpderetta 5y ago
What about multiprocessing? I assume that MirageOS can take advantage of multiple cores (or do you need separate instances per core?). In this case is the system still shared memory? Also I would say there are reasons for isolation beyond memory safety.
- hannesm 5y ago
  MirageOS is - similar to the latest OCaml release - only using a single CPU core. You can run multiple unikernels, one on each core. If doing that, you can use Xen vchan (shared memory), or TCP for marshalling. > Also I would say there are reasons for isolation beyond memory safety. Would you mind to elaborate which reasons you are thinking of?
  - 0xbkt 5y ago
    > only using a single CPU core How does it go when you deploy a unikernel on EC2 (or on any IaaS where the hypervisor is managed unlike bare-metal) with multiple cores? Is there a way to start a unikernel per core on a single instance, or are you bound to use single core instance types only?
  - gpderetta 5y ago
    > MirageOS is - similar to the latest OCaml release - only using a single CPU core. Thanks. Is that going to change now that OCaml is finally getting proper multicore support? >> Also I would say there are reasons for isolation beyond memory safety. >Would you mind to elaborate which reasons you are thinking of? Memory safety in a sense protects the integrity of the 'runtime', but only partially help to protect business level integrity. A task might still tricked (by mistake or malice) to access objects it is not supposed to. I'm sure that OCaml has enough abstractions to help prevent that, but full isolation of tasks is a blunt and effective tool.

asymmetric 5y ago

Is this also how you deal with logging/monitoring? Do you have a concept of logging daemon? How would I run prometheus exporter-like things? Is there a FAQ where questions along these lines are answered?

avsm 5y ago
Just substitute 'microservice' with 'unikernel' and you do broadly the same things. There's a prometheus library that you link with the MirageOS unikernel and it exports using that: https://github.com/mirage/prometheus https://github.com/mirage/prometheus No FAQ for this sort of thing yet, but we should start assembling one sometime soon. Questions like this very welcome on the discussion forums: https://discuss.ocaml.org/t/ann-mirageos-4-0/9598 https://discuss.ocaml.org/t/ann-mirageos-4-0/9598 to help us get started. There's a nice collection of unikernels over at: https://github.com/roburio/unikernels https://github.com/roburio/unikernels and https://github.com/tarides/unikernels https://github.com/tarides/unikernels for various infrastructure pieces (like https, smtp, dns, ip filters, etc) that are good to crib from for your own infrastructure.
hannesm 5y ago
Maybe https://hannes.robur.coop/Posts/Monitoring https://hannes.robur.coop/Posts/Monitoring sheds some light how to monitor MirageOS unikernels ;)

scns 5y ago

Conurrency instead of parallelism.

wmf 5y ago
No amount of concurrency on a single core can equal the performance of multiple cores.
- pjmlp 5y ago
  That is why you deploy a process per core, with affinity so that it doesn't jump around.
- cestith 5y ago
  You can run more than one unikernel per machine. That's why things like KVM or Bhyve are targets instead of just bare metal.

gpderetta 5y ago

What about multiprocessing? I assume that MirageOS can take advantage of multiple cores (or do you need separate instances per core?). In this case is the system still shared memory? Also I would say there are reasons for isolation beyond memory safety.

hannesm 5y ago
MirageOS is - similar to the latest OCaml release - only using a single CPU core. You can run multiple unikernels, one on each core. If doing that, you can use Xen vchan (shared memory), or TCP for marshalling. > Also I would say there are reasons for isolation beyond memory safety. Would you mind to elaborate which reasons you are thinking of?
- 0xbkt 5y ago
  > only using a single CPU core How does it go when you deploy a unikernel on EC2 (or on any IaaS where the hypervisor is managed unlike bare-metal) with multiple cores? Is there a way to start a unikernel per core on a single instance, or are you bound to use single core instance types only?
- gpderetta 5y ago
  > MirageOS is - similar to the latest OCaml release - only using a single CPU core. Thanks. Is that going to change now that OCaml is finally getting proper multicore support? >> Also I would say there are reasons for isolation beyond memory safety. >Would you mind to elaborate which reasons you are thinking of? Memory safety in a sense protects the integrity of the 'runtime', but only partially help to protect business level integrity. A task might still tricked (by mistake or malice) to access objects it is not supposed to. I'm sure that OCaml has enough abstractions to help prevent that, but full isolation of tasks is a blunt and effective tool.