A synchronous interface to Node's net.Socket

Usage no npm install needed!

<script type="module">
  import syncSocket from '';



This Node.js module exposes a no-dependency class called SyncSocket, which acts as a synchronous interface to Node's net.Socket instance, which is normally only asynchronous.

This module exposes many of the same methods and properties a normal net.Socket has.


SyncSocket is slow. Not unusably slow, but you should have a good reason to want to use it. This was made for the rare case you need blocking read/writes in your Node.js application.

In addition, another one of my modules, netlinkwrapper exposes a similar synchronous socket. However that module requires node-gyp to compile. SyncSocket does not require node-gyp. In fact, it has no dependencies.

How Does it Work?

tl;dr: I abuse child_process.execFileSync.

I've done some pretty thorough research into how Node's net.Socket module works, and you can't make it synchronous without rewriting it in C++ via node-gyp, or using some modules like fibers that in turn would depend on node-gyp anyways.

With that in mind I've devised this hack that abuses child processes.

One process, the worker, is spawned that uses the normal net module doing read/writes asynchronously as you should to net.Sockets. It then creates a TCP server to allow requests to its net.Socket.

Then another file, the query script, acts as a script that will request something from the worker, and spit the result out to stdout once it has the results, again gotten asynchronously.

Now from our main thread we can abuse child_process.execFileSync, which executes the query script, which then queries our worker process, and exits with the result.

Obviously this is a ton of overhead just to avoid callbacks. But it works.


I've ran some tests, and SyncSocket is about 20 times slower in doing read/writes than my competing module netlinkwrapper. So if node-gyp is not an issue to you, use that instead. Or really just use net.Socket.