Increase Allocated memory CF2016

Charlie, I was until now unaware of Carl's G1GC post in this very forum or of his other Adobe post on G1GC. Writing that in 2013 - hats off to him. He was well ahead of the times. Both are useful references. 

Bkbk, can you offer a reference that supports your assertion that everyone using cf should switch to g1gc? You don't offer any caveat or limitation, so you do seem to be asserting that.

 

I've simply never seen any such contention made that it's the right choice for all. I do realize it's the default gc algo if an alternative is not offered, but since cf has always and does still specifically set parallelgc, and you are suggesting that people change it, that's why I'm asking, in the behalf of all reading this.

By @Charlie Arehart

I do not assert that everyone using CF should switch to G1GC. I am only recommending G1GC in @ghanna1 's specific use-case.

The use-case consists of:

1.  Heap-size greater than 6 GB. 
2. 1100 transactions a second;
3. 4000 devices in the field that check in every 5 seconds and another 10,000 devices that check in every hour.
4. Then add the rest of our traffic and ... estimate around 1100 per second.

You can deduce from 1., 2., 3. and 4: a large heap size, plus the need for reduced garbage-collection pause-times. That is, for this use-case, pause-time minimization or increased request-processing-speed (G1GC) would be preferable to throughput maximization or increased volume of requests processed (ParallelGC).

https://docs.oracle.com/javase/8/docs/technotes/guides/vm/gctuning/g1_gc.html

In any case, for applications that have a substantial heap-size, say, 4 GB or more, G1GC is Oracle Java's default garbage collector. That has been so from JDK 9 onwards.

Granted, ColdFusion still uses ParallelGC as default. However, I would bet the following. Were you to present the above use-case to Adobe's ColdFusion Team, they too would recommend G1GC. 

1100 cf page requests per second would be quite impressive, for a single CF instance. This is not about whether cf can handle it, I just mean that it's an unusually high number.

I'd be curious how you're measuring that. Might that really be your web server, which processes far more than just cf page requests? Or maybe more than one cf instance?

If you may wonder why I'd press this point, well as Dave said, often raising the heap is secondary to finding why it's needed. Of course, if you were at cf's default heap max of 1024mb, I'd not be surprised by a need to raise the heap for 1100 rps. Heck, even people running only a few requests per second often find they need more than that 1gb default. 🙂 That may be all you need. 

Sometimes only a few gig is enough, sometimes several, rarely dozens. And of course the box has to have room to provide for that. But I'm saying that sometimes the "better" solution is to understand what's causing cf heap use to rise (and be unable to GC).

And if your 1100 rps might be unusual even for your cf server (compared to previous days or weeks), perhaps THAT is a place to look into unexpected "pressure".

Finally, you show fr's tracking of heap. You won't be raising the allocated but the max. The jvm decides how much within the max to "allocate" at any time, driven by heap "use" (and whether its doing gc's is freeing up heap). Indeed, sometimes the real focus of troubleshooting cf "memory" problems indeed finding what's ending up in the heap but that can't be gc'ed. 

BTW, now that I notice the fr screenshot, is it indeed fr showing 1100 requests per second? If so, that's great! 

HTH.