Logstash grokparsefailure

my serio:
filebeat read log info from file, then kafka, logstash consume log from kafka and write elasticsearch.
But sometimes, in logstash ,there are half-baked log (a section of a log event), so grok parse failure;
sometimes, log is messy code;
why? someone help??
thanks!

It's completely impossible to help without additional details. What do you the broken log entries look like? What does your configuration look like?