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PM2 is very good and I really wonder why it's still somewhat unknown. People complaining that Node.js only use one CPU core, or benchmarks with low scores for

PM2 is very good and I really wonder why it's still somewhat unknown. People complaining that Node.js only use one CPU core, or benchmarks with low scores for Node.js. There are solutions for this! PM2 is one of them and is very good. Use it.

nesarkvechnep 3y ago
Just spawn more processes. Great solution! /s
- sublinear 3y ago
  Would you rather scale with more containers? That's heavier. Properly written node apps are bound by I/O throughput. CPU and memory cost for additional processes is minimal, but latency is significantly decreased with a worker pool.
  - jitl 3y ago
    > Properly written node apps are bound by I/O throughput Does that mean that node apps shouldn’t do any computation on data, just move bytes between a file and a network socket? If I need my program to think, I wrote it wrong or in the wrong language? I would rather have shared memory multithreading be a usable feature in my program’s runtime. SharedArrayBuffer exists but 98% of existing code uses objects and arrays so can’t be easily shared between processes without copying, and the cost of copying objects with structuredClone puts a huge optimization barrier in between most code and parallel processing.
    - sublinear 3y ago
      No, just write your javascript to do more I/O than compute. Apps should do app things not low level tasks that slow things down. If you need to compute something complicated, write it in a compiled language and make it a node module. Many popular npm libraries are exactly this.
      - nesarkvechnep 3y ago
        Or… don’t write Node at all? I’d choose Elixir over Node any day.
    - throwitaway1123 3y ago
      > Does that mean that node apps shouldn’t do any computation on data, just move bytes between a file and a network socket? If I need my program to think, I wrote it wrong or in the wrong language? This is a very uncharitable interpretation of Node's primary use case. I think it would be more accurate to say don't use Node if all of the following apply: - Your task is CPU bound rather than IO bound (e.g. you're not waiting to insert or retrieve data from the database). - Your task is highly parallel (some computations are sequential and linear). You can't use worker threads because: - You have too much data to bear the cost of message passing via the structured clone algorithm. - You can't share memory and avoid structured cloning because your data can't be represented using an array buffer. This is a far cry from the claim that Node can't handle problems that require "thinking". When you're on the JIT compiler's happy path Node can think pretty quickly actually. In practice, many high volume web servers are handling enough requests that there's more than enough jobs for each Node process to have exclusivity over its jobs, and you don't need to share work between processes. Each process or worker thread can be largely independent. Not every task is going to fall within those boundaries, but that's ok, Node doesn't have to fulfill every use case.
- mort96 3y ago
  I mean... yes
bionhoward 3y ago
PM2 is a life saver for sidestepping Kubernetes imho
chamomeal 3y ago
How do you feel about using pm2 inside of a container? At work, most of our app is docker-composed in one VPS (early B2B product with few customers). I would like to have the multiple-process benefits of PM2, but I don’t want to spin up a whole load balancer for it, or split the node service from the other services. Everything is so simple right now and I’d like to keep it that way lol. Last time I googled this I found conflicting opinions, but if I can just stuff PM2 into my node container, I’d be a happy dev!
- ilaksh 3y ago
  Node.js cluster https://nodejs.org/api/cluster.html https://nodejs.org/api/cluster.html or worker_threads
- dalore 3y ago
  We use PM2 in a docker container since we got a memory leak and PM2 has a memory limiter option that allows us to kill and restart a process when it uses too much memory. If we let it grow the response time starts to drop due to GC taking longer and longer.
hosh 3y ago
You have to do so many things just to use more than a single CPU core. There are other language platforms and runtimes where using up the entire available CPU cores is the default option, and taking advantage of multiple cores within the app is easy by design. I can see why people like pm2, similarly to why I can see why people like Nodejs. But I think pm2 is half-baked, and Nodejs's greatest design feature (single-threaded async execution) is flawed by design.
andrewmcwatters 3y ago
pm2 is the de facto process manager for Node.js. I don't think it's "somewhat unknown."
- jasonjmcghee 3y ago
  Many don’t take the time to do some research to figure out “what’s the right way to be doing this? What do i need to search for?” You write nodemon or npm start- and so it's put at the end of the Dockerfile as such. I know someone that discovered pm2 because copilot autocompleted their Dockerfile that way.

nesarkvechnep 3y ago

Just spawn more processes. Great solution! /s

sublinear 3y ago
Would you rather scale with more containers? That's heavier. Properly written node apps are bound by I/O throughput. CPU and memory cost for additional processes is minimal, but latency is significantly decreased with a worker pool.
- jitl 3y ago
  > Properly written node apps are bound by I/O throughput Does that mean that node apps shouldn’t do any computation on data, just move bytes between a file and a network socket? If I need my program to think, I wrote it wrong or in the wrong language? I would rather have shared memory multithreading be a usable feature in my program’s runtime. SharedArrayBuffer exists but 98% of existing code uses objects and arrays so can’t be easily shared between processes without copying, and the cost of copying objects with structuredClone puts a huge optimization barrier in between most code and parallel processing.
  - sublinear 3y ago
    No, just write your javascript to do more I/O than compute. Apps should do app things not low level tasks that slow things down. If you need to compute something complicated, write it in a compiled language and make it a node module. Many popular npm libraries are exactly this.
    - nesarkvechnep 3y ago
      Or… don’t write Node at all? I’d choose Elixir over Node any day.
  - throwitaway1123 3y ago
    > Does that mean that node apps shouldn’t do any computation on data, just move bytes between a file and a network socket? If I need my program to think, I wrote it wrong or in the wrong language? This is a very uncharitable interpretation of Node's primary use case. I think it would be more accurate to say don't use Node if all of the following apply: - Your task is CPU bound rather than IO bound (e.g. you're not waiting to insert or retrieve data from the database). - Your task is highly parallel (some computations are sequential and linear). You can't use worker threads because: - You have too much data to bear the cost of message passing via the structured clone algorithm. - You can't share memory and avoid structured cloning because your data can't be represented using an array buffer. This is a far cry from the claim that Node can't handle problems that require "thinking". When you're on the JIT compiler's happy path Node can think pretty quickly actually. In practice, many high volume web servers are handling enough requests that there's more than enough jobs for each Node process to have exclusivity over its jobs, and you don't need to share work between processes. Each process or worker thread can be largely independent. Not every task is going to fall within those boundaries, but that's ok, Node doesn't have to fulfill every use case.
mort96 3y ago
I mean... yes

bionhoward 3y ago

PM2 is a life saver for sidestepping Kubernetes imho

chamomeal 3y ago

How do you feel about using pm2 inside of a container? At work, most of our app is docker-composed in one VPS (early B2B product with few customers). I would like to have the multiple-process benefits of PM2, but I don’t want to spin up a whole load balancer for it, or split the node service from the other services. Everything is so simple right now and I’d like to keep it that way lol. Last time I googled this I found conflicting opinions, but if I can just stuff PM2 into my node container, I’d be a happy dev!

ilaksh 3y ago
Node.js cluster https://nodejs.org/api/cluster.html https://nodejs.org/api/cluster.html or worker_threads
dalore 3y ago
We use PM2 in a docker container since we got a memory leak and PM2 has a memory limiter option that allows us to kill and restart a process when it uses too much memory. If we let it grow the response time starts to drop due to GC taking longer and longer.

hosh 3y ago

You have to do so many things just to use more than a single CPU core. There are other language platforms and runtimes where using up the entire available CPU cores is the default option, and taking advantage of multiple cores within the app is easy by design. I can see why people like pm2, similarly to why I can see why people like Nodejs. But I think pm2 is half-baked, and Nodejs's greatest design feature (single-threaded async execution) is flawed by design.

andrewmcwatters 3y ago

pm2 is the de facto process manager for Node.js. I don't think it's "somewhat unknown."

jasonjmcghee 3y ago
Many don’t take the time to do some research to figure out “what’s the right way to be doing this? What do i need to search for?” You write nodemon or npm start- and so it's put at the end of the Dockerfile as such. I know someone that discovered pm2 because copilot autocompleted their Dockerfile that way.