6 ms·

OTP = Open Telecom Platform [1], though I think the full name is avoided nowadays. On an unrelated note, I've always been fascinated with the Erlang VM. The id

OTP = Open Telecom Platform [1], though I think the full name is avoided nowadays. On an unrelated note, I've always been fascinated with the Erlang VM. The idea that you could hot-load modules and have multiple versions of the same module running at once seems really useful. I wonder why other runtimes haven't adopted these features? [1] https://en.wikipedia.org/wiki/Open_Telecom_Platform https://en.wikipedia.org/wiki/Open_Telecom_Platform

yetihehe 6y ago
> I wonder why other runtimes haven't adopted these features? Probably mainly due to shared memory. When you know your data can be modified only in one place, changing data structure is easier. Try changing a struct when some other code is using it. It would require a lock for every object in memory.
- macintux 6y ago
  One of the great things about Erlang and the BEAM is that by designing a very opinionated language around concepts like immutability and ubiquitous messaging between lightweight actors, you can define the VM to support those. So there’s this collection of features between the language and VM that support each other, and are generally hard to reproduce outside that ecosystem because they are so interdependent.
- dnautics 6y ago
  the fact that looping through a process is a tail call which by its very nature creates well-defined boundaries (both in "code segment" and in "data segment") also helps a gazillion. Try doing hot loading in the middle of a while loop... Not saying it's impossible, but you're not gonna have a good time.
rectang 6y ago
Or "One Time Password" if you're an idiot like me. Gotta love an introductory article on "OTP" which even includes a section entitled "What is OTP?" but doesn't expand the acronym.
- deleted 6y ago
  [deleted]
- dnautics 6y ago
  It's no longer considered a correct acronym as erlang is not really a telecoms language anymore. It's been a problem where outsiders are quick to think or say, "I am not writing a telecoms app" and dismiss it.
  - rectang 6y ago
    I understand this reasoning. The conclusion I draw is that "OTP" is truly a miserable name — like "car cdr" level bad. As a newcomer to Elixir's OTP, I cannot divine that experts hold the opinion that the acronym expansion is misleading when that information is deliberately withheld. The first thing this article did was send me off to search the web. Folks should use a backronym, like "Opinionated Threading Platform".
    - dnautics 6y ago
      Back in the 90s there were plenty of programs which ditched their acronyms: elm, pine, pico, gnu, etc.
      - IggleSniggle 6y ago
        Importantly, all of those have a discernible pronunciation that is not simply stating the letters in order.
        dnautics 6y ago
        a very good point. That goes for GNU, too.
Thaxll 6y ago
Because why would you do that? Now we have tool and pipeline where testing / deploying ect .. is easy, so I'm not sure why would I risk to do hot load things. I don't think it's useful and I think it's pretty dangerous is the first place. You have code that can run two different things, wcgw.
- dmitriid 6y ago
  A very erlang demo showed upgrading code running on a telephone switch without dropping the call. That's why you want hot code loading.
  - Thaxll 6y ago
    Because control plane does not handle anything phone related most likely? It's like upgrading Kubernates masters, your API servers still works and are not affected. AFAIK Erlang code does not handle any network traffic, all of that is done in C/C++.
    - dmitriid 6y ago
      This is the original video in its 90s glory: https://www.youtube.com/watch?v=uKfKtXYLG78 https://www.youtube.com/watch?v=uKfKtXYLG78 Regardless of where the call is handled, you can't just deploy a new switch in a telecom network, but you still want to upgrade them. This is where you really want hot code loading.
      - yetihehe 6y ago
        Real world usage case - I have a server which handles several thousand telematic devices (telemetry+actuation), split into about 20 different device types. It's small device base so doesn't require multiple servers and we can be really cheap. But requiring to disconnect all devices just to make one small change to one device driver would be painful. Now we can have uptime of over half a year and in that time we had changes/fixes to several drivers. Normally that would require scheduled downtime every week and slow us down considerably.
taywrobel 6y ago
Then they really need to pick a new name, because OTP is widely understood in programming to be a “One-Time Pad”, and without defining what they think it means in this context this is the least coherent article I’ve read in a while.
- jaggirs 6y ago
  Cryptography \neq Programming
- carlmr 6y ago
  I never heard of your OTP, and I immediately knew which OTP they were talking about due to the Elixir keyword.
  - taywrobel 6y ago
    Do you program in elixir often?
    - carlmr 6y ago
      No, never, but I did a tutorial once a few years ago since i wanted to know what's so cool about the language.
sheenobu 6y ago
OSGi (Open Services Gateway initiative) [1] provides this for the JVM by modularizing the ClassLoader [2]. If a module is upgraded but classes from the previous version are still referenced by other modules, both modules will run. An OSGi "service" is not an actor but, like OTP with servers+supervisors, is the logical unit with which you build your systems. "bundles" (Java JARs with additional metadata) then act as the equivalent "application" that contain the services. Outside of it being Java, I have strong opinions (positive and negative) that I've decided not to include. [1] https://en.wikipedia.org/wiki/OSGi https://en.wikipedia.org/wiki/OSGi [2] https://en.wikipedia.org/wiki/Java_Classloader https://en.wikipedia.org/wiki/Java_Classloader
simscitizen 6y ago
Hot loading in Erlang is not magical. Here is an example. Let's say you want to redeploy some new code. In your deploy, you change some existing function foo in module A to call a new function bar in module B. If you do this, you'd better make sure that you hotload the new version of B before you hotload the new version of A. Otherwise some process could end up trying to call B:bar through A:foo before the new B has finished loading. If you rely on hotloading modules as your primary deploy mechanism, you will run into issues like this all the time. So it's not really clear to me that hotloading is a win for your typical stateless web service compared to just deploying a new binary and doing your standard zero-downtime deploy via forking. It makes more sense when you realize that certain Erlang apps build up a huge amount of state in-memory. In those cases hotloading allows you to load new versions of the changed modules without having to take down the whole VM.

yetihehe 6y ago

> I wonder why other runtimes haven't adopted these features? Probably mainly due to shared memory. When you know your data can be modified only in one place, changing data structure is easier. Try changing a struct when some other code is using it. It would require a lock for every object in memory.

macintux 6y ago
One of the great things about Erlang and the BEAM is that by designing a very opinionated language around concepts like immutability and ubiquitous messaging between lightweight actors, you can define the VM to support those. So there’s this collection of features between the language and VM that support each other, and are generally hard to reproduce outside that ecosystem because they are so interdependent.
dnautics 6y ago
the fact that looping through a process is a tail call which by its very nature creates well-defined boundaries (both in "code segment" and in "data segment") also helps a gazillion. Try doing hot loading in the middle of a while loop... Not saying it's impossible, but you're not gonna have a good time.

rectang 6y ago

Or "One Time Password" if you're an idiot like me. Gotta love an introductory article on "OTP" which even includes a section entitled "What is OTP?" but doesn't expand the acronym.

deleted 6y ago
[deleted]
dnautics 6y ago
It's no longer considered a correct acronym as erlang is not really a telecoms language anymore. It's been a problem where outsiders are quick to think or say, "I am not writing a telecoms app" and dismiss it.
- rectang 6y ago
  I understand this reasoning. The conclusion I draw is that "OTP" is truly a miserable name — like "car cdr" level bad. As a newcomer to Elixir's OTP, I cannot divine that experts hold the opinion that the acronym expansion is misleading when that information is deliberately withheld. The first thing this article did was send me off to search the web. Folks should use a backronym, like "Opinionated Threading Platform".
  - dnautics 6y ago
    Back in the 90s there were plenty of programs which ditched their acronyms: elm, pine, pico, gnu, etc.
    - IggleSniggle 6y ago
      Importantly, all of those have a discernible pronunciation that is not simply stating the letters in order.
      - dnautics 6y ago
        a very good point. That goes for GNU, too.

Thaxll 6y ago

Because why would you do that? Now we have tool and pipeline where testing / deploying ect .. is easy, so I'm not sure why would I risk to do hot load things. I don't think it's useful and I think it's pretty dangerous is the first place. You have code that can run two different things, wcgw.

dmitriid 6y ago
A very erlang demo showed upgrading code running on a telephone switch without dropping the call. That's why you want hot code loading.
- Thaxll 6y ago
  Because control plane does not handle anything phone related most likely? It's like upgrading Kubernates masters, your API servers still works and are not affected. AFAIK Erlang code does not handle any network traffic, all of that is done in C/C++.
  - dmitriid 6y ago
    This is the original video in its 90s glory: https://www.youtube.com/watch?v=uKfKtXYLG78 https://www.youtube.com/watch?v=uKfKtXYLG78 Regardless of where the call is handled, you can't just deploy a new switch in a telecom network, but you still want to upgrade them. This is where you really want hot code loading.
    - yetihehe 6y ago
      Real world usage case - I have a server which handles several thousand telematic devices (telemetry+actuation), split into about 20 different device types. It's small device base so doesn't require multiple servers and we can be really cheap. But requiring to disconnect all devices just to make one small change to one device driver would be painful. Now we can have uptime of over half a year and in that time we had changes/fixes to several drivers. Normally that would require scheduled downtime every week and slow us down considerably.

taywrobel 6y ago

Then they really need to pick a new name, because OTP is widely understood in programming to be a “One-Time Pad”, and without defining what they think it means in this context this is the least coherent article I’ve read in a while.

jaggirs 6y ago
Cryptography \neq Programming
carlmr 6y ago
I never heard of your OTP, and I immediately knew which OTP they were talking about due to the Elixir keyword.
- taywrobel 6y ago
  Do you program in elixir often?
  - carlmr 6y ago
    No, never, but I did a tutorial once a few years ago since i wanted to know what's so cool about the language.

sheenobu 6y ago

OSGi (Open Services Gateway initiative) [1] provides this for the JVM by modularizing the ClassLoader [2]. If a module is upgraded but classes from the previous version are still referenced by other modules, both modules will run. An OSGi "service" is not an actor but, like OTP with servers+supervisors, is the logical unit with which you build your systems. "bundles" (Java JARs with additional metadata) then act as the equivalent "application" that contain the services. Outside of it being Java, I have strong opinions (positive and negative) that I've decided not to include. [1] https://en.wikipedia.org/wiki/OSGi https://en.wikipedia.org/wiki/OSGi [2] https://en.wikipedia.org/wiki/Java_Classloader https://en.wikipedia.org/wiki/Java_Classloader

simscitizen 6y ago

Hot loading in Erlang is not magical. Here is an example. Let's say you want to redeploy some new code. In your deploy, you change some existing function foo in module A to call a new function bar in module B. If you do this, you'd better make sure that you hotload the new version of B before you hotload the new version of A. Otherwise some process could end up trying to call B:bar through A:foo before the new B has finished loading. If you rely on hotloading modules as your primary deploy mechanism, you will run into issues like this all the time. So it's not really clear to me that hotloading is a win for your typical stateless web service compared to just deploying a new binary and doing your standard zero-downtime deploy via forking. It makes more sense when you realize that certain Erlang apps build up a huge amount of state in-memory. In those cases hotloading allows you to load new versions of the changed modules without having to take down the whole VM.