On 13/04/2021 00:11, Jerry Malcolm wrote:
I'm getting TC crashes (ver 8.5) with "out of memory" errors.
What is the exact error message? There are multiple different problems
that all get reported with an OutOfMemoryException and the detail of the
exception will tell you (and us) which it is.
I
understand heap space and the parameters to set it. But I need a bit of
help with "out of memory", not "out of heap space". This is running in
an EC2 on AWS. It's a development server, so activity is minimal
compared to production. We also are running it on a smaller EC2 which
is likely contributing to the problem. But interestingly the last crash
happened in the middle of the night. The last request came in 15
minutes prior to the crash, and it was some php intrusion attempt URL
that returned 404. Crashes don't happen often. A couple of servers have
failed once or twice a week. And this is the first time the dev server
crashed. But I still really need to get a handle on it.
We have a pretty large max heap space configured. Does this problem
have something to do with specifying a heap space larger than TC can
allocate with physical memory? I figured there was still the option of
virtual memory and swapping if it ran out of physical memory.
The heap space isn't the only memory the JVM needs. It also needs memory
for:
- the JVM code
- classes
- thread stacks
- native libraries
- managing GC
and a bunch of other things I have probably forgotten.
I need to learn more and tuning the memory usage. Is there some formula
that tells me the max heap space given a certain size of physical
memory? Or is there something else I'm totally missing about memory
configuration?
There is no fixed formula to determine total memory requirements for a
given heap as it is very application dependent. Once you know which
particular OOME issue you are hitting, then you can figure out the right
response.
Mark
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