[erlang-questions] Memory usage by Mnesia growing to fast and it seems very strange

Dmitriy Gorbenko <>
Mon Dec 17 16:25:19 CET 2007


We have done again few test, and find that if we shall do transaction
writing, memory usage will grow.
If we will use dirty commands, then memory growing, but not so fast, and
sometimes (and it's interesting fact) even did not grow at all.

Ok, even if we use transactions to operate with Mnesia for about 500 000
times, and Mnesia accumulate 40-60 megabytes, after a few minutes of
idle (beam process is idle - nothing to do to him), memory usage will
fall to 9-11 megabytes. And this gives me opinion to think that Mnesia
under heavy load just delay "free memory" procedure  until "better time"
comes. And then this time is come - memory usage very quickly decrease.

Is my assumption right ?

Thanks.

Dmitriy Gorbenko wrote:
> Hi all.
>
> Well, I have two .erl files, which makes Mnesia allocating a lot of
> memory and vary fast.
>
> What they are doing ? First file wrote to Mnesia table some values, and
> then into loop tries to read this value.
> Second file only writes to mnesia table in loop, and nothing else.
>
> You can find in this two test ties to use flags like "fullsweep_after",
> but they also did not help - memory continue constantly growing.
>
>
> So, If anyone knows why those test produces so much memory usage, please
> - reply me.
>
>
> Inside the files, you can find small readme, how to run them.
>   
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