5 ms·

I think it's important to mention that an important part of erlang's failure domain driven mentality is not just "let it crash", but also tying together failure

I think it's important to mention that an important part of erlang's failure domain driven mentality is not just "let it crash", but also tying together failure domains: what should you also bring down with you when you crash. For example. Your data sync task encounter an http error in a connected SAAS that threatens data inconsistency. Perfect time to crash. But if you do so, also take down the database connection so that the connection can be returned to the connection pool and the transaction you're running in can be rolled back, ideally without having to try/catch and keep track/selectively recycle of all of cumulative responsibilities that have accrued in that task.

continuational 5y ago
This is so important. Too many asynchronous solution simply don't support cancellation, and instead just keep chugging along, doing undesirable things while wasting cpu & ram.
- bullen 5y ago
  RAM yes, CPU should not waste while waiting for an async. non-blocking request. Apache web server also crashes safely when some PHP script leaks memory, but if you have a proper VM with GC this is something of the past. Fortunately most web systems use Java or it's copy C# at this point and that is not going to change since Erlang has a simple memory model that cannot do joint parallel tasks. Go has no VM, WASM has no GC, rust is too slow to compile... that leaves plain C with a C++ compiler but you don't want to have that on a server because assembly seg. faults. So on the server you have to use Java. Not EE but SE.
  - hnedeotes 5y ago
    > Erlang has a simple memory model that cannot do joint parallel tasks. What do you mean?
    - bullen 5y ago
      You have to copy memory before sharing it between threads. You cannot do atomic memory sharing between threads = threads cannot work on the same task at the "same" time efficiently.
      - hnedeotes 5y ago
        That's actually much a feature. Many problems can still be done quite efficiently, for instance stream parsing a file you can have each N newlines being sent to different processes, and the same with many other problems that can be sliced, traversing nested collections, fetching batches of records from stores, etc. Sometimes you can also reformulate the problem, but yes not all problems fit. I would add though that whenever you want to write orchestration around that parallel work it's much easier in erlang than the alternatives.
        bullen 5y ago
        Maybe, but some problems, like making a MMO server cannot be solved with Erlang. So everyone that uses this inferior tech is wasting their and humanitys time. Erlang was designed to make many 1-on-1 phonecalls, it's terrible for almost everything else and today 1-on-1 does not exist just like obsolete TV is unidirectional. In the future everything is many 1-to-many (requires joint parallelism) and that is the final protocol just like the final medium is 3D! We need to sharpen up and make the best tools. C (client) and JavaSE (server) are unsuperceded for decades. it's time to stop fragmenting the programmers workspace and co-operate instead. If you use any other languages you are in the wrong and history will prove you to be a wasteful person.
        AllegedAlec 5y ago
        > If you use any other language you are in the wrong and history will prove you to be a wasteful person. You're an idiot. Not because of your choice of tools, but because of your dogmatic shittalking of others for preferring other tools.
  - dnautics 5y ago
    There are enough escape hatches in erlang to efficiently do "joint parallel tasks" when you need them.
BoiledCabbage 5y ago
The linked SO provides a great description of the philosophy/benefits of Erlang. > Erlang has several features that remove human working time as a source of downtime: > Hot code reloading. In an Erlang system, it is easy to compile and load a replacement module for an existing one. The BEAM emulator does the swap automatically without apparently stopping anything. There is doubtless some tiny amount of time during which this transfer happens, but it's happening automatically in computer time, rather than manually in human time. This makes it possible to do upgrades with essentially zero downtime. (You could have downtime if the replacement module has a bug which crashes the system, but that's why you test before deploying to production.) > Supervisors. Erlang's OTP library has a supervisory framework built into it which lets you define how the system should react if a module crashes. The standard action here is to restart the failed module. Assuming the restarted module doesn't immediately crash again, the total downtime charged against your system might be a matter of milliseconds. A solid system that hardly ever crashes might indeed accumulate only a fraction of a second of total downtime over the course of years of run time. > Processes. These correspond roughly to threads in other languages, except that they do not share state except through persistent data stores. Other than that, communication happens via message passing. Because Erlang processes are very inexpensive (far cheaper than OS threads) this encourages a loosely-coupled design, so that if a process dies, only one tiny part of the system experiences downtime. Typically, the supervisor restarts that one process, with little to no impact on the rest of the system. > Asynchronous message passing. When one process wants to tell another something, there is a first-class operator in the Erlang language that lets it do that. The message sending process doesn't have to wait for the receiver to process the message, and it doesn't have to coordinate ownership of data sent. The asynchronous functional nature of Erlang's message-passing system takes care of all that. This helps maintain high uptimes because it reduces the effect that downtime in one part of a system can have on other parts. > Clustering. This follows from the previous point: Erlang's message passing mechanism works transparently between machines on a network, so a sending process doesn't even have to care that the receiver is on a separate machine. This provides an easy mechanism for dividing a workload up among many machines, each of which can go down separately without harming overall system uptime. 1. https://stackoverflow.com/questions/8426897/erlangs-99-9999999-nine-nines-reliability https://stackoverflow.com/questions/8426897/erlangs-99-99999...

continuational 5y ago

This is so important. Too many asynchronous solution simply don't support cancellation, and instead just keep chugging along, doing undesirable things while wasting cpu & ram.

bullen 5y ago
RAM yes, CPU should not waste while waiting for an async. non-blocking request. Apache web server also crashes safely when some PHP script leaks memory, but if you have a proper VM with GC this is something of the past. Fortunately most web systems use Java or it's copy C# at this point and that is not going to change since Erlang has a simple memory model that cannot do joint parallel tasks. Go has no VM, WASM has no GC, rust is too slow to compile... that leaves plain C with a C++ compiler but you don't want to have that on a server because assembly seg. faults. So on the server you have to use Java. Not EE but SE.
- hnedeotes 5y ago
  > Erlang has a simple memory model that cannot do joint parallel tasks. What do you mean?
  - bullen 5y ago
    You have to copy memory before sharing it between threads. You cannot do atomic memory sharing between threads = threads cannot work on the same task at the "same" time efficiently.
    - hnedeotes 5y ago
      That's actually much a feature. Many problems can still be done quite efficiently, for instance stream parsing a file you can have each N newlines being sent to different processes, and the same with many other problems that can be sliced, traversing nested collections, fetching batches of records from stores, etc. Sometimes you can also reformulate the problem, but yes not all problems fit. I would add though that whenever you want to write orchestration around that parallel work it's much easier in erlang than the alternatives.
      - bullen 5y ago
        Maybe, but some problems, like making a MMO server cannot be solved with Erlang. So everyone that uses this inferior tech is wasting their and humanitys time. Erlang was designed to make many 1-on-1 phonecalls, it's terrible for almost everything else and today 1-on-1 does not exist just like obsolete TV is unidirectional. In the future everything is many 1-to-many (requires joint parallelism) and that is the final protocol just like the final medium is 3D! We need to sharpen up and make the best tools. C (client) and JavaSE (server) are unsuperceded for decades. it's time to stop fragmenting the programmers workspace and co-operate instead. If you use any other languages you are in the wrong and history will prove you to be a wasteful person.
        AllegedAlec 5y ago
        > If you use any other language you are in the wrong and history will prove you to be a wasteful person. You're an idiot. Not because of your choice of tools, but because of your dogmatic shittalking of others for preferring other tools.
- dnautics 5y ago
  There are enough escape hatches in erlang to efficiently do "joint parallel tasks" when you need them.

BoiledCabbage 5y ago

The linked SO provides a great description of the philosophy/benefits of Erlang. > Erlang has several features that remove human working time as a source of downtime: > Hot code reloading. In an Erlang system, it is easy to compile and load a replacement module for an existing one. The BEAM emulator does the swap automatically without apparently stopping anything. There is doubtless some tiny amount of time during which this transfer happens, but it's happening automatically in computer time, rather than manually in human time. This makes it possible to do upgrades with essentially zero downtime. (You could have downtime if the replacement module has a bug which crashes the system, but that's why you test before deploying to production.) > Supervisors. Erlang's OTP library has a supervisory framework built into it which lets you define how the system should react if a module crashes. The standard action here is to restart the failed module. Assuming the restarted module doesn't immediately crash again, the total downtime charged against your system might be a matter of milliseconds. A solid system that hardly ever crashes might indeed accumulate only a fraction of a second of total downtime over the course of years of run time. > Processes. These correspond roughly to threads in other languages, except that they do not share state except through persistent data stores. Other than that, communication happens via message passing. Because Erlang processes are very inexpensive (far cheaper than OS threads) this encourages a loosely-coupled design, so that if a process dies, only one tiny part of the system experiences downtime. Typically, the supervisor restarts that one process, with little to no impact on the rest of the system. > Asynchronous message passing. When one process wants to tell another something, there is a first-class operator in the Erlang language that lets it do that. The message sending process doesn't have to wait for the receiver to process the message, and it doesn't have to coordinate ownership of data sent. The asynchronous functional nature of Erlang's message-passing system takes care of all that. This helps maintain high uptimes because it reduces the effect that downtime in one part of a system can have on other parts. > Clustering. This follows from the previous point: Erlang's message passing mechanism works transparently between machines on a network, so a sending process doesn't even have to care that the receiver is on a separate machine. This provides an easy mechanism for dividing a workload up among many machines, each of which can go down separately without harming overall system uptime. 1. https://stackoverflow.com/questions/8426897/erlangs-99-9999999-nine-nines-reliability https://stackoverflow.com/questions/8426897/erlangs-99-99999...