Omniscope Classic Hotspot errors - Native memory allocation (mmap)

Modified on Tue, 13 Jul 2021 at 12:16 PM

This is article is aimed at users who are using Omniscope Classic and are getting Hotspot errors

Those errors are are not expected behaviour, but that is not to say they can't happen when you open large IOK files. Omniscope Classic is an in-memory based application, as opposed to Evo, which has a different memory model altogether, and only needs a few GB of memory for similar data volumes (but benefits from fast SSD disk instead). It is recommended that you consider using Omniscope Evo if you are working in large datasets.

Omniscope Classic instance is configured (by default) to use up to 75% of the memory on your system. It starts with a much smaller allocation and increases the amount of memory it uses as needed up to this maximum. This is a reasonable choice for systems where only one Omniscope instance is the primary consumer of memory.

The somewhat catastrophic error you're seeing is appearing because the operating system was unable to 'honour the request' to give it some of that memory. This can be due to other processes (including OS core processes, and multiple Omniscope instances) also taking up memory.

To resolve this issue you need to manage memory allocation configuration in Omniscope and follow the rule:

[total memory needed by all processes at a given point in time
must be less than 
[physical memory] plus [max pagefile size].

You can find detailed instructions how to manage memory allocation here.

You should either limit this scenario (only use one Omniscope instance when looking at big files) or reduce the configured memory allocation by editing MAX_MEMORY_MB in

Also try to exit and restart Omniscope after closing a very large IOK file to ensure that Omniscope is not retaining OS memory unnecessarily.

Was this article helpful?

That’s Great!

Thank you for your feedback

Sorry! We couldn't be helpful

Thank you for your feedback

Let us know how can we improve this article!

Select atleast one of the reasons
CAPTCHA verification is required.

Feedback sent

We appreciate your effort and will try to fix the article