JVM memory alert

Report · Mar 21, 2012

Hi all,

A few days ago my server started sending me alerts avbout the JVM memory allocation exceeding the set alert threshold of 450 megs. So, I raised the alert to 786 megs as I have a min of 1024 and max of 2048 set as the heap.

Now I am getting the alerts at 786 megs. They have been coming in every 10-15 minutes for the past 3 days. Anyone have an idea how to find the leak? I have been looking at the snapshot sent with the alerts and it all seems in order.

This is CF9 Enterprise 9,0,1,274733 running on Linux ES5 8 gigs ram

this is a production server with one high end client and several low traffic sites. The sessions are set to timeout after 30 min and the application times out after 2 days.

Any suggestions will be appreciated.

Report · Mar 21, 2012

If you have 8gb of RAM why not allocate more to CF? I doubt its a "leak" as you expect, though thats possible. The sites I run, for example, are farily low traffic but we give no less than 6gb of RAM to CF. It depends on your application, the number of users (sessions are stored in memory, for example).

So, sorry I can't be of more help, but you should consider that it may not be a leak. You may also want to set the heap min and max to the same value. This will help increase performance so the JVM doesn't have to reallocate memory as the heap grows, it will allocate the max right from the start.

Report · Mar 21, 2012

Thanks for the quick responce sean. I was thinking "leak" because the server has been running for over a year without one single alert then out of nowhere I get one every 10 minutes for 3 day straight. I originaly had the min and max heap at the same settings but I have seen conflicting info on that so I thought I would set it with offset amounts to see if there was diffrence. I have not seen one to date. I suppose I could ramp up the ram as there is plenty to spare at this point. I am more interested in what happened to spike the use. I suppose I will look at my web stats and see if there are some clues in there.

Report · Mar 21, 2012

Obviously I haven't seen it so I could be way off, but my first guess would be the number of sessions open. For example, if you have a bunch of search engine spiders that hit your site, they create lots and lots of sessions. They don't keep cookies so each time they hit your site, they start a new session. This could really increase the amount of RAM being used while its spidering the site.