Crash eval_beamsearch_ngram.py code for large data sets
@VahidooX 
Hi,
When we use [`eval_beamsearch_ngram.py`](https://github.com/NVIDIA/NeMo/blob/main/scripts/asr_language_modeling/ngram_lm/eval_beamsearch_ngram.py) code for large data sets (e.g., with 500,000 utterances), the code crashes after some hours of computation (i.e., the OS kill automatically the process!!). According to my observation, the code runs correctly when the ASR acoustic model runs and the raw transcriptions of data sets extracted correctly, but when the LM wants to apply in a huge amount of raw transcriptions then it crashes. I googled this issue, and I found below link (which I think the issue related to the shortage of memory of the server):
- [Unable to allocate array with shape and data type](https://stackoverflow.com/questions/57507832/unable-to-allocate-array-with-shape-and-data-type)   
According to the above-mentioned link, I have changed the `overcommit_memory` mode of my server. however, unfortunately the issue didn't resolved. Would you please help me to address the issue?
Thanks a lot