I tend to use appendpipe to avoid race conditions, to my understanding it pauses the search while it processes everything up to that point before opening up the appendpipe.
| appendpipe [ | makeresults | fields - _time ]
https://docs.splunk.com/Documentation/Splunk/8.0.0/SearchReference/Appendpipe
"Appends the result of the subpipeline to the search results. Unlike a subsearch, the subpipeline is not run first. The subpipeline is run when the search reaches the appendpipe command. "
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