CODEWITHSUNDEEP
node.js
goxarad784
goxarad784

Reputation: 435

Nodejs clusters performance improvement?

I was watching this video about Nodejs clusterning where you can spawn off several child process. He said that the parent cluster takes care of the child cluster in a round-robin approach giving a chunk of time to each child process. Why would that be any different than the running a single thread? Unless each child can handle itself I do not see much benefit of doing so. However, in the end he pulls some benchmark that is really good which makes me wonder why do people even use a none clustered app if having clusters improves performance by that much.

Upvotes: 1

Views: 543

Answers (1)

jfriend00
jfriend00

Reputation: 707466

This statement: "the parent cluster takes care of the child cluster in a round-robin approach giving a chunk of time to each child process" is not entirely correct.

Each cluster process is a separate OS process. The operating system takes care of sharing the CPU among processes, not the parent process. The parent process takes each incoming http request and splits them among the child processes, but that is the extent of the parent process' involvement.

If there is only one CPU core in the server hardware (not usually the case these days unless you're on a hosting plan that only gives you access to one CPU core), then that single CPU core is shared among all of your processes/threads that are active and wish to be running.

If there is more than one CPU core, then individual processes can be assigned to separate cores and your processes can be running truly in parallel. This is where the biggest advantage comes from with nodejs clustering. Then, you get multiple requests truly running in parallel rather than in a single thread as it would be with a single nodejs process.

However, in the end he pulls some benchmark that is really good which makes me wonder why do people even use a non-clustered app if having clusters improves performance by that much.

Clustering adds some level of complication. For example, if you have any server-side state that is kept in memory within your server process that all incoming requests need access to, then that won't work with clustered processes because all the clustered processes don't have access to the same memory (they each have their own memory). In that case, you typically have to either remove any server-side state or move all the server-side state to it's own process (usually a database) that all the clustered processes can then access. This is very doable, but adds an extra level of complication and has its own performance implications.

In addition clustering takes more memory on your server. It may also require more monitoring and logging to make sure all processes are running healthy.

Upvotes: 5

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