Some questions about garbage collector

Question

Question

Norman W. Freeman · Jul 18, 2023

Hello,

I am looking for information about garbage collector. I already looked at documentation but I could not find anything about it.
Here is some questions :

1) is there a garbage collector per process (each process has it's own memory and GC is done per process) or is it global (eg: shared memory) ?
I know there is some memory allocated per process at startup but also globally (gmheap).

2) when a GC / cleanup occurs somewhere, is it possible that it block the other processes for a short moment ? (eg: a "stop the world" GC that pause everything while job is being done).

3) is it possible to gather information about GC in portal or using some utility ? (Eg: number of GCs, how much time it took, ...).

Note : this question is not related to global buffers (which AFAIK is a totally different thing).

Product version: IRIS 2021.1

$ZV: IRIS for Windows (x86-64) 2021.1 (Build 215U) Wed Jun 9 2021 09:39:22 EDT

Discussion (3)2

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Vic Sun · Jul 18, 2023

The garbage collector is somewhat an internal process which is why I believe it is sparsely documented. I'd echo Dmitry that understanding your concern would help.

I think what is documented generally covers a high level understanding - that being that there is a GARCOL process. And that blocks are marked freed after a large kill by this process, to be freed in the background.

1 0

score 0 · Answer 1 · 2023-07-18T08:50:42-04:00

What is the actual concern, then?

From my experience on different systems with highload, I did not see effects, that could point to think about it.

score 0 · Answer 2 · 2023-07-24T08:40:10-04:00

Echoing what Vic and Dmitry have mentioned. GARCOL cleans up large KILLs, so it's a database operation. Your post seems to ask a different question, akin to Java object garbage collection.

I've been quite surprised to see how much work gets done by IRIS processes with scant process memory; I suppose because it's so easy to use globals.

Understanding what you are experiencing and trying to do would help a lot.