Why do I receive errors when running a Campaign?

Environment: 

Oracle B2C Service Console

Issue:

We sometimes receive the following error:

Internal Error
    File: msgbase.c
    Line: 130
  In Fcn: msg_open
  Called Fcn: mmap() returned -1
Description: mmap of /cgi-bin/site.db/wl/en_US/nlp_lexicon.wl failed, errno=12.
If multi-editing, reducing the number of records selected may solve this problem.

Resolution:

If you see such an error in the error log resulting from a Campaign run, it could be due to one of the following reasons:

1. Campaign audience is too large 
   
   To resolve this, split the audience used for the Campaign into smaller groups of objects to be processed by the Campaign.
   
   
2. Rules and/or External Events are not being suppressed
   
   If you are using a Custom Process Model (CPM) in the process, use suppression as described in Answer ID 8392: SPM/Process Designer Best Practices.
   
   
3. More rules than necessary are firing
   
   Rules should be arranged so that each object processed touches as few rules as possible.