JavaScript heap out of memory after message processing ends

[Steve-Mcl]

Hi, welcome to the forum.

@KronwarsCZ

While testing, I can see a sudden jump in CPU usage to 100% and memory jump from normal 950MB to 1.2 GB, followed by a crash.

@KronwarsCZ

As far as I can tell, the message is processed and no loop is happening

I know, but really does smell like an uncontrolled loop (or recursion)

@KronwarsCZ

Do you have any ideas as to why this might be happening

There are many threads on the forum for this topic: Search results for '"JavaScript heap out of memory" order:latest' - Node-RED Forum

This one was a little different.

@Steve-Mcl

The error get thrown in a variety of situations, here are a few:

• When attempting to process large amounts of data or execute complex algorithms that require a lot of memory.
• When running a Node.js server with a large number of connections or concurrent requests.
• When running a Node.js application in a container or virtual machine with limited memory resources.

which was resolved like this:

@Steve-Mcl

we do add --max_old_space_size=512. What that means is when this heap fills up, Node.js needs to perform a garbage collection (GC) cycle. Coupled with your comment about "now not able to modify flows" (my mind reads "you have recently modified flows") from that, I dont think it is a stretch to conclude something has changed and the GC is now unable able to keep up with memory allocations.

Are you able to try something out? If possible, edit the file lib/launcher.js in your device agent installation and change the line to something like '--max_old_space_size=1024' (or remove it altogether)

Where you set max_old_space_size will depend on how you are running node-red (do a search)

but the 100% CPU spike really really smells like a hard, blocking loop - so perhaps a buggy contrib? or some recursive (self calling) function node code? or an invisible loop caused by link nodes or MQTT?